Recieving Shadow on Custom Shader

Basically I've got this custom shader for silhouette highlight from Unity3d Wiki... (I Know nothing about Shaders... purely programming background). I want this Shader to recieve shadow casted by other objects

Shader code:

 Shader "Outlined/Silhouetted Diffuse" {
     Properties{
         _Color("Main Color", Color) = (.5,.5,.5,1)
         _OutlineColor("Outline Color", Color) = (0,0,0,1)
         _Outline("Outline width", Range(0.0, 0.03)) = .005
         _MainTex("Base (RGB)", 2D) = "white" { }
     }
 
         CGINCLUDE 
 #include "UnityCG.cginc"
 
     struct appdata {
         float4 vertex : POSITION;
         float3 normal : NORMAL;
     };
 
     struct v2f {
         float4 pos : POSITION;
         float4 color : COLOR;
     };
 
     uniform float _Outline;
     uniform float4 _OutlineColor;
 
     v2f vert(appdata v) {
         // just make a copy of incoming vertex data but scaled according to normal direction
         v2f o;
         o.pos = UnityObjectToClipPos(v.vertex);
 
         float3 norm = mul((float3x3)UNITY_MATRIX_IT_MV, v.normal);
         float2 offset = TransformViewToProjection(norm.xy);
 
         o.pos.xy += offset * o.pos.z * _Outline;
         o.color = _OutlineColor;
         return o;
     }
     ENDCG
 
         SubShader{
         Tags{ "Queue" = "Transparent" }
 
         // note that a vertex shader is specified here but its using the one above
         Pass{
         Name "OUTLINE"
         Tags{ "LightMode" = "Always" }
         Cull Off
         ZWrite Off
         ZTest Always
         ColorMask RGB // alpha not used
 
                       // you can choose what kind of blending mode you want for the outline
         Blend SrcAlpha OneMinusSrcAlpha // Normal
                                         //Blend One One // Additive
                                         //Blend One OneMinusDstColor // Soft Additive
                                         //Blend DstColor Zero // Multiplicative
                                         //Blend DstColor SrcColor // 2x Multiplicative
 
         CGPROGRAM
 #pragma vertex vert
 #pragma fragment frag
 
         half4 frag(v2f i) :COLOR{
         return i.color;
     }
         ENDCG
     }
 
         Pass{
         Name "BASE"
         ZWrite On
         ZTest LEqual
         Blend SrcAlpha OneMinusSrcAlpha
         Material{
         Diffuse[_Color]
         Ambient[_Color]
     }
         Lighting On
         SetTexture[_MainTex]{
         ConstantColor[_Color]
         Combine texture * constant
     }
         SetTexture[_MainTex]{
         Combine previous * primary DOUBLE
     }
     }
     }
 
         SubShader{
         Tags{ "Queue" = "Transparent" }
 
         Pass{
         Name "OUTLINE"
         Tags{ "LightMode" = "Always" }
         Cull Front
         ZWrite Off
         ZTest Always
         ColorMask RGB
 
         // you can choose what kind of blending mode you want for the outline
         Blend SrcAlpha OneMinusSrcAlpha // Normal
                                         //Blend One One // Additive
                                         //Blend One OneMinusDstColor // Soft Additive
                                         //Blend DstColor Zero // Multiplicative
                                         //Blend DstColor SrcColor // 2x Multiplicative
 
         CGPROGRAM
 #pragma vertex vert
 #pragma exclude_renderers gles xbox360 ps3
         ENDCG
         SetTexture[_MainTex]{ combine primary }
     }
 
         Pass{
         Name "BASE"
         ZWrite On
         ZTest LEqual
         Blend SrcAlpha OneMinusSrcAlpha
         Material{
         Diffuse[_Color]
         Ambient[_Color]
     }
         Lighting On
         SetTexture[_MainTex]{
         ConstantColor[_Color]
         Combine texture * constant
     }
         SetTexture[_MainTex]{
         Combine previous * primary DOUBLE
     }
     }
     }
 
         Fallback "Diffuse"
 }