Z-Depth Doesnt Work :(

I’ve been fiddling with this for hours now and the best i can get apart from an all black or white screen is this:

What does ‘clamp output’ mean?

There are no threads specific to this except that i understand the default units in sketchup is inches? Anyhoo - i tried plugging in all manner of numbers in the boxes and thats the best i can get :frowning:

Any help much appreciated!

D