ZBrushCentral

Disappearing bump map during render (Maya)

Does anybody know why a bump map would stop rendering after converting a subd object back to polys?

I converted my original poly head to subd and rendered with bump and displacement and it worked fine. To see if there were any difference in render times I wanted to try using polys, so I converted the subd to back to polys and reapplied everything including the approximation nodes. Displacement rendered fine, but no bump. I take the displacment off the poly head and the bump renders.

I even tried setting up a new scene with the original poly head and still no go.
What am I missing?

are you using maya’s renderer?

Whoops sorry… I am using Mental Ray. I have also tried editing alpha gain and color offsets, but nada.