GetPerPixelLightAttenuation(ScreenUV); Broken?

return
GetPerPixelLightAttenuation(ScreenUV);

Hello all you helpful people!
To start with my project is set up to use forward shading and what I’m currently trying to access is the shadow pass.
When using this within a custom node appears to be returning random texture information from memory in screen space… I’ve seen tiled grids, other random prop textures from the scene, and even dilated font sheets projected from the output.

so i’m at a loss for what i need to use to get the shadow pass…any ideas?