weird with ComputeScreenPos(),Help!!!!

[Lulucifer]

Here is my Shader:

Shader "Shadow/ShadowMapping/ShadowMappingReciever_4" {
	SubShader {
		Tags { "RenderType"="Opaque" }
		pass{
		ZTest Always
		ZWrite off
		CGPROGRAM
		#pragma vertex vert
		#pragma fragment frag
		#include "UnityCG.cginc"
		
		//sampler2D _myShadow;
		//sampler2D _myZDepth;
		float4x4 _myShadowProj;
		
		sampler2D _CameraDepthTexture;
		float4x4 _CameraToWorld;
		
		struct vertOut {
			float4 pos:SV_POSITION;
			float4 texc:TEXCOORD0;
			float4 scrPos;
		};
		vertOut vert(appdata_base v)
		{
			float4x4 proj;
			proj=mul(_myShadowProj,_Object2World);
			
			vertOut o;
			o.pos=mul(UNITY_MATRIX_MVP,v.vertex);
			o.texc=mul(proj,v.vertex);
			o.scrPos=ComputeScreenPos(o.pos);
			
			return o;
		}
		float4 frag(vertOut i):COLOR
		{
			float d=tex2Dproj(_CameraDepthTexture,UNITY_PROJ_COORD(i.scrPos)).r;
			d=Linear01Depth(d);
			return d;
		}
		ENDCG
		}//endpass
	} 
	//FallBack "Diffuse"
}

I think it should result something like this:

But it always result this:

What should i do,
here is the scene:

[Lulucifer]

Interesting, when i comment out this two line code,it works

vertOut vert(appdata_base v)
		{
			float4x4 proj;
			//proj=mul(_myShadowProj,_Object2World);
			
			vertOut o;
			o.pos=mul(UNITY_MATRIX_MVP,v.vertex);
			//o.texc=mul(proj,v.vertex);
			o.scrPos=ComputeScreenPos(o.pos);
			
			return o;
		}

//proj=mul(_myShadowProj,_Object2World);
//o.texc=mul(proj,v.vertex);
but these two line code has nothing to do with ComputeScreenPos(),Doesnt it?
SO why does this interesting thing happens?

[Lulucifer]

I got it,it has somehing wrong with the available TEXCOORD,
Like this ,will fix it.

struct vertOut {
			float4 pos:SV_POSITION;
			float4 texc:TEXCOORD0;
			float4 scrPos:TEXCOORD1;
		};

but still werid,why does it happens in this way?
Anyone?

It seems my fault,because of dual GPU Card?