How can I access GBufferVelocity

I’m almost sure that I can’t help you but still…

What are the compile errors?

My end goal is to output a postprocess material that outputs per-pixel velocities from the previous to current frame.
UE4 already has pixel velocities implemented for use in their motion blur pipeline, I simply need to extract it from the gbuffer UE4 shader source

First I am using a custom material node and trying to extract the gbuffer by GetGBufferData(float2 uv, bool normalize) but I am running into compile errors.
To test basic usage, my custom node has 0 inputs and 1 output, a float1.

My usage -

GBufferData gbuffer = GetGBufferData(float2(0, 0), false);
return 1.0

this is also a problem - currently the live preview just shows up as “dirty” and no errors are outputted. It simply hangs. If i comment out the first line it renders a white screen (correct) which made me think line 1 was giving a compile error.
I can’t for the life of me find the compile button or the errors in the material editor either.