Surface Reflection Shader with Shadows

I'm not sure how to get this shader to display shadows. It completely ignores the shadows cast by my light whereas all other surfaces receive them no problem. I've looked around, but I don't know anything about writing shaders.

Here's the shader I'm using. Can anyone help please?

 Shader "FX/Surface Reflection"
 { 
     Properties
     {
         _MainAlpha("MainAlpha", Range(0, 1)) = 1
         _ReflectionAlpha("ReflectionAlpha", Range(0, 1)) = 1
         _TintColor ("Tint Color (RGB)", Color) = (1,1,1)
         _MainTex ("MainTex (RGBA)", 2D) = ""
         _ReflectionTex ("ReflectionTex", 2D) = "white" { TexGen ObjectLinear }
     }
  
     //Two texture cards: full thing
     Subshader
     { 
         Tags {Queue = Transparent}
         ZWrite Off
         Colormask RGBA
         Color [_TintColor]
         Blend SrcAlpha OneMinusSrcAlpha
         Pass
         {
             SetTexture[_ReflectionTex] { constantColor(0,0,0, [_ReflectionAlpha]) matrix [_ProjMatrix] combine texture * previous, constant} 
         }
         Pass
         {
             SetTexture[_MainTex] { constantColor(0,0,0, [_MainAlpha]) combine texture * primary, texture * constant}
         }
     }
  
     //Fallback: just main texture
     Subshader
     {
         Pass
         {
             SetTexture [_MainTex] { combine texture }
         }
     }
 }

And here is the sourcecode to the Surface Reflection script attached to the gameObject.

 using UnityEngine;
 using System.Collections;
 
 //This is in fact just the Water script from Pro Standard Assets,
 //just with refraction stuff removed.
 
 [ExecuteInEditMode] //Make reflection live-update even when not in play mode
 public class SurfaceReflection : MonoBehaviour
 {
     public bool m_DisablePixelLights = true;
     public int m_TextureSize = 256;
     public float m_clipPlaneOffset = 0.07f;
     private float m_finalClipPlaneOffset = 0.0f;
     public bool m_NormalsFromMesh = false;
     public bool m_BaseClipOffsetFromMesh = false;
     public bool m_BaseClipOffsetFromMeshInverted = false;
     private Vector3 m_calculatedNormal = Vector3.zero;
     
     public LayerMask m_ReflectLayers = -1;
     
     private Hashtable m_ReflectionCameras = new Hashtable(); //Camera -> Camera table
     
     private RenderTexture m_ReflectionTexture = null;
     private int m_OldReflectionTextureSize = 0;
     
     private static bool s_InsideRendering = false;
     
     //This is called when it's known that the object will be rendered by some
     //camera. We render reflections and do other updates here.
     //Because the script executes in edit mode, reflections for the scene view
     //camera will just work!
     public void OnWillRenderObject()
     {
         if(!enabled || !renderer || !renderer.sharedMaterial || !renderer.enabled)
             return;
         
         Camera cam = Camera.current;
         if(!cam)
             return;
         
         if(m_NormalsFromMesh && GetComponent<MeshFilter>() != null)
             m_calculatedNormal = transform.TransformDirection(GetComponent<MeshFilter>().sharedMesh.normals[0]);
         
         if(m_BaseClipOffsetFromMesh && GetComponent<MeshFilter>() != null)
             m_finalClipPlaneOffset = (transform.position - transform.TransformPoint(GetComponent<MeshFilter>().sharedMesh.vertices[0])).magnitude + m_clipPlaneOffset;
         else if(m_BaseClipOffsetFromMeshInverted && GetComponent<MeshFilter>() != null)
             m_finalClipPlaneOffset = -(transform.position - transform.TransformPoint(GetComponent<MeshFilter>().sharedMesh.vertices[0])).magnitude + m_clipPlaneOffset;
         else
             m_finalClipPlaneOffset = m_clipPlaneOffset;
         
         //Safeguard from recursive reflections.        
         if(s_InsideRendering)
             return;
         s_InsideRendering = true;
         
         Camera reflectionCamera;
         CreateSurfaceObjects(cam, out reflectionCamera);
         
         //Find out the reflection plane: position and normal in world space
         Vector3 pos = transform.position;
         Vector3 normal = m_NormalsFromMesh && GetComponent<MeshFilter>() != null ? m_calculatedNormal : transform.up;
         
         //Optionally disable pixel lights for reflection
         int oldPixelLightCount = QualitySettings.pixelLightCount;
         if(m_DisablePixelLights)
             QualitySettings.pixelLightCount = 0;
         
         UpdateCameraModes(cam, reflectionCamera);
         
         //Render reflection
         //Reflect camera around reflection plane
         float d = -Vector3.Dot (normal, pos) - m_finalClipPlaneOffset;
         Vector4 reflectionPlane = new Vector4 (normal.x, normal.y, normal.z, d);
         
         Matrix4x4 reflection = Matrix4x4.zero;
         CalculateReflectionMatrix (ref reflection, reflectionPlane);
         Vector3 oldpos = cam.transform.position;
         Vector3 newpos = reflection.MultiplyPoint(oldpos);
         reflectionCamera.worldToCameraMatrix = cam.worldToCameraMatrix * reflection;
         
         //Setup oblique projection matrix so that near plane is our reflection plane.
         //This way we clip everything below/above it for free.
         Vector4 clipPlane = CameraSpacePlane(reflectionCamera, pos, normal, 1.0f);
         Matrix4x4 projection = cam.projectionMatrix;
         CalculateObliqueMatrix (ref projection, clipPlane);
         reflectionCamera.projectionMatrix = projection;
         
         reflectionCamera.cullingMask = ~(1<<4) & m_ReflectLayers.value; //never render water layer
         reflectionCamera.targetTexture = m_ReflectionTexture;
         GL.SetRevertBackfacing (true);
         reflectionCamera.transform.position = newpos;
         Vector3 euler = cam.transform.eulerAngles;
         reflectionCamera.transform.eulerAngles = new Vector3(0, euler.y, euler.z);
         reflectionCamera.Render();
         reflectionCamera.transform.position = oldpos;
         GL.SetRevertBackfacing (false);
         Material[] materials = renderer.sharedMaterials;
         foreach(Material mat in materials)
         {
             if(mat.HasProperty("_ReflectionTex"))
                 mat.SetTexture("_ReflectionTex", m_ReflectionTexture);
         }
         
         //Set matrix on the shader that transforms UVs from object space into screen
         //space. We want to just project reflection texture on screen.
         Matrix4x4 scaleOffset = Matrix4x4.TRS(
             new Vector3(0.5f,0.5f,0.5f), Quaternion.identity, new Vector3(0.5f,0.5f,0.5f));
         Vector3 scale = transform.lossyScale;
         Matrix4x4 mtx = transform.localToWorldMatrix * Matrix4x4.Scale(new Vector3(1.0f/scale.x, 1.0f/scale.y, 1.0f/scale.z));
         mtx = scaleOffset * cam.projectionMatrix * cam.worldToCameraMatrix * mtx;
         foreach(Material mat in materials)
             mat.SetMatrix("_ProjMatrix", mtx);
         
         //Restore pixel light count
         if(m_DisablePixelLights)
             QualitySettings.pixelLightCount = oldPixelLightCount;
         
         s_InsideRendering = false;
     }
     
     
     //Cleanup all the objects we possibly have created
     void OnDisable()
     {
         if(m_ReflectionTexture)
         {
             DestroyImmediate(m_ReflectionTexture);
             m_ReflectionTexture = null;
         }
         foreach(DictionaryEntry kvp in m_ReflectionCameras)
             DestroyImmediate(((Camera)kvp.Value).gameObject);
         m_ReflectionCameras.Clear();
     }
     
     
     private void UpdateCameraModes(Camera src, Camera dest)
     {
         if(dest == null)
             return;
         //set camera to clear the same way as current camera
         dest.clearFlags = src.clearFlags;
         dest.backgroundColor = src.backgroundColor;        
         if(src.clearFlags == CameraClearFlags.Skybox)
         {
             Skybox sky = src.GetComponent(typeof(Skybox)) as Skybox;
             Skybox mysky = dest.GetComponent(typeof(Skybox)) as Skybox;
             if(!sky || !sky.material)
             {
                 mysky.enabled = false;
             }
             else
             {
                 mysky.enabled = true;
                 mysky.material = sky.material;
             }
         }
         //update other values to match current camera.
         //even if we are supplying custom camera&projection matrices,
         //some of values are used elsewhere (e.g. skybox uses far plane)
         dest.farClipPlane = src.farClipPlane;
         dest.nearClipPlane = src.nearClipPlane;
         dest.orthographic = src.orthographic;
         dest.fieldOfView = src.fieldOfView;
         dest.aspect = src.aspect;
         dest.orthographicSize = src.orthographicSize;
     }
     
     //On-demand create any objects we need
     private void CreateSurfaceObjects(Camera currentCamera, out Camera reflectionCamera)
     {
         reflectionCamera = null;
         
         //Reflection render texture
         if(!m_ReflectionTexture || m_OldReflectionTextureSize != m_TextureSize)
         {
             if(m_ReflectionTexture)
                 DestroyImmediate(m_ReflectionTexture);
             m_ReflectionTexture = new RenderTexture(m_TextureSize, m_TextureSize, 16);
             m_ReflectionTexture.name = "__SurfaceReflection" + GetInstanceID();
             m_ReflectionTexture.isPowerOfTwo = true;
             m_ReflectionTexture.hideFlags = HideFlags.DontSave;
             m_OldReflectionTextureSize = m_TextureSize;
         }
         
         //Camera for reflection
         reflectionCamera = m_ReflectionCameras[currentCamera] as Camera;
         if(!reflectionCamera) //catch both not-in-dictionary and in-dictionary-but-deleted-GO
         {
             GameObject go = new GameObject("Surface Refl Camera id" + GetInstanceID() + " for " + currentCamera.GetInstanceID(), typeof(Camera), typeof(Skybox));
             reflectionCamera = go.camera;
             reflectionCamera.enabled = false;
             reflectionCamera.transform.position = transform.position;
             reflectionCamera.transform.rotation = transform.rotation;
             reflectionCamera.gameObject.AddComponent("FlareLayer");
             go.hideFlags = HideFlags.HideAndDontSave;
             m_ReflectionCameras[currentCamera] = reflectionCamera;
         }        
     }
     
     //Extended sign: returns -1, 0 or 1 based on sign of a
     private static float sgn(float a)
     {
         if (a > 0.0f) return 1.0f;
         if (a < 0.0f) return -1.0f;
         return 0.0f;
     }
     
     //Given position/normal of the plane, calculates plane in camera space.
     private Vector4 CameraSpacePlane (Camera cam, Vector3 pos, Vector3 normal, float sideSign)
     {
         Vector3 offsetPos = pos + normal * m_finalClipPlaneOffset;
         Matrix4x4 m = cam.worldToCameraMatrix;
         Vector3 cpos = m.MultiplyPoint(offsetPos);
         Vector3 cnormal = m.MultiplyVector(normal).normalized * sideSign;
         return new Vector4(cnormal.x, cnormal.y, cnormal.z, -Vector3.Dot(cpos,cnormal));
     }
     
     //Adjusts the given projection matrix so that near plane is the given clipPlane
     //clipPlane is given in camera space. See article in Game Programming Gems 5 and
     //http://aras-p.info/texts/obliqueortho.html
     private static void CalculateObliqueMatrix (ref Matrix4x4 projection, Vector4 clipPlane)
     {
         Vector4 q = projection.inverse * new Vector4(
             sgn(clipPlane.x),
             sgn(clipPlane.y),
             1.0f,
             1.0f
             );
         Vector4 c = clipPlane * (2.0F / (Vector4.Dot (clipPlane, q)));
         //third row = clip plane - fourth row
         projection[2] = c.x - projection[3];
         projection[6] = c.y - projection[7];
         projection[10] = c.z - projection[11];
         projection[14] = c.w - projection[15];
     }
     
     //Calculates reflection matrix around the given plane
     private static void CalculateReflectionMatrix (ref Matrix4x4 reflectionMat, Vector4 plane)
     {
         reflectionMat.m00 = (1F - 2F*plane[0]*plane[0]);
         reflectionMat.m01 = (  - 2F*plane[0]*plane[1]);
         reflectionMat.m02 = (  - 2F*plane[0]*plane[2]);
         reflectionMat.m03 = (  - 2F*plane[3]*plane[0]);
         
         reflectionMat.m10 = (  - 2F*plane[1]*plane[0]);
         reflectionMat.m11 = (1F - 2F*plane[1]*plane[1]);
         reflectionMat.m12 = (  - 2F*plane[1]*plane[2]);
         reflectionMat.m13 = (  - 2F*plane[3]*plane[1]);
         
         reflectionMat.m20 = (  - 2F*plane[2]*plane[0]);
         reflectionMat.m21 = (  - 2F*plane[2]*plane[1]);
         reflectionMat.m22 = (1F - 2F*plane[2]*plane[2]);
         reflectionMat.m23 = (  - 2F*plane[3]*plane[2]);
         
         reflectionMat.m30 = 0F;
         reflectionMat.m31 = 0F;
         reflectionMat.m32 = 0F;
         reflectionMat.m33 = 1F;
     }
 }