Why does my mirror not reflect my water shader?

 using UnityEngine;
 using System.Collections;
 
 // This is in fact just the Water script from Pro Standard Assets,
 // just with refraction stuff removed.
 
 [ExecuteInEditMode] // Make mirror live-update even when not in play mode
 public class MirrorReflection : MonoBehaviour
 {
     public bool m_DisablePixelLights = true;
     public int m_TextureSize = 256;
     public float m_ClipPlaneOffset = 0.07f;
 
     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()
     {
         var rend = GetComponent<Renderer>();
         if (!enabled || !rend || !rend.sharedMaterial || !rend.enabled)
             return;
 
         Camera cam = Camera.current;
         if (!cam)
             return;
 
         // Safeguard from recursive reflections.        
         if (s_InsideRendering)
             return;
         s_InsideRendering = true;
 
         Camera reflectionCamera;
         CreateMirrorObjects(cam, out reflectionCamera);
 
         // find out the reflection plane: position and normal in world space
         Vector3 pos = transform.position;
         Vector3 normal = 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_ClipPlaneOffset;
         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;
         Matrix4x4 projection = cam.CalculateObliqueMatrix(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 = rend.sharedMaterials;
         foreach (Material mat in materials)
         {
             if (mat.HasProperty("_ReflectionTex"))
                 mat.SetTexture("_ReflectionTex", m_ReflectionTexture);
         }
 
         // 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 CreateMirrorObjects(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 = "__MirrorReflection" + 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("Mirror Refl Camera id" + GetInstanceID() + " for " + currentCamera.GetInstanceID(), typeof(Camera), typeof(Skybox));
             reflectionCamera = go.GetComponent<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_ClipPlaneOffset;
         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));
     }
 
     // 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;
     }
 }