Shader renders black when using GrabPass

I've run into a problem recently, with the GrabPass command in ShaderLab.

It seems that as soon as that little command is added to a program, it will output completely black and unlit, even if the shader was working fine until then and it doesn't even touch the GrabTexture.

I posted this on the ShaderLab subforum, and with help from the community was able to deduce that it wasn't a problem with my code, but in fact a technical issue in Unity, that apparently only appears on certain systems.

Has anyone else noticed this problem with shaders using GrabPass, and is there a way to fix it?

I'm using Windows 8 Pro x64, Unity 4.o.1 and made sure to update to the latest graphics drivers. My CPU is an Intel Core 2 Duo, and the graphics card a GeForce 460 SE. I know these are not exactly state of the art, so does GrabPass only work on newer hardware?

 

I've got the exact same problem. Does anyone know the solution to this?

 

Same here

 

In my case,windows and android display grabpass shader right.But when it comes to iOS,once the grabpass shader object is in the field of view of camera,the whole screen becomes black(except UI elements),and the screen gets back to normal only when the grabpass shader object gets out of field of view.It only happens on iOS.Don't know if it is a Unity bug or something.

 

Does anyone know the solution to this?

 

Do you know the solution to this?

 

Does anyone know the solution to this?