Android - Updating Sampler2D at runtime not working

I am trying to send video camera data to my shader at runtime. (Also, tried with just a plain video) Everything works great in the PC version but when I build to android all I get is a grey screen. Here is the code I have in the frag section. Any idea why this is not working on Android? Also did not work on WebGL.

Code (CSharp):

1.             float4 frag (v2f i) : SV_Target
2.             {  
3.                     float4 back    = tex2D(_BufferTexture, i.uv);
4.                     float4 front = tex2D(_Buffer2Texture, i.uv);
5.                     float4 change = (front - back);      
6.                     return change;

In the camera script I have

Code (CSharp):

1. void Update () {
2.         if (Cam.didUpdateThisFrame)
3.         {
4.             Graphics.CopyTexture(Cam, _Buffer2Texture);
5.             //I also update the BufferTexture but a frame back
6.         }
7.  
8. }

I only posted the relevant parts of the code.
Thanks

 

bump

 

https://docs.unity3d.com/ScriptReference/Rendering.CopyTextureSupport.html

 

Yup that was the problem... Thanks bgolus.
Is there any other way to do what I am trying without CopyTexture?

 

Graphics.Blit()?

 

Yeah I tried that too, I get the same results.
I think it is more or less equivalent to Graphics.CopyTexture.