Immage effect detect edges (geometry) not working.

I got a problem with the image effect "Edge Detection (Geometry)". It simply wont work, i did try a new scene, a new project even, but the result is the same every time, nothing is happening. I can set the "Edges only" var to set the screen to a selected color, but because it is not drawing the edges the result is a completely empty screen.

The other edge shaders like Edge Detection (Color) and Crease are working perfectly, and my hardware supports all image effects.
What am i doing wrong?