its saying there was no PoserSurface node found in that material.

The script is going to try looking at all materials in all figures in that scene. Before the tracebacks you should get printed to the screen the figure name its currently examining.

Check that figure manually to make sure it actually has materials.

 

n = tree.NodeByInternalName("PoserSurface")

if n:
      i = n.InputByInternalName("Diffuse_Value")
      i.SetFloat(0.8)
      tree.UpdatePreview()

 

 

make this change should get you past the problem as a quick fix.