[Solved] Screen space UVs inside a canvas (RawImage Material) - not rendering

It works on a normal quad. As soon as I apply it as a material on an Image or RawImage in a uGUI canvas, it disappears. It looks correct in the editor window, but doesn't render in-game. I'm on b20 atm.

The shader I'm testing with: http://pastebin.com/7u6pMNQY

Is this a bug? Is it something I'm not supposed to try and do?

edit: I had the canvas set to Screen Space - Overlay. Screen Space - Camera fixed it. Duh.