Weight painting doesn't work on part of a mesh

I’m having a strange problem with weight painting a mesh. Part of a mesh i’m trying to animate with an armature is shown in dark blue and another part in black. I can weight paint the dark blue part but not the dark part. Any known solution to this problem or is this a bug? I’m using Blender 2.45.

are the faces hidden in face mode? you can hit the F key to enter UV face select mode, and Alt-H to reveal any hidden faces, then F-key back to object mode. this is a useful way to only work with specific vertices when weight painting. this behaviour has changed in the latest version.

if that isn’t the problem, then i am stumped. you may need to post a screenshot.

jim ww

Are you trying to paint with SubDiv modifier? It could be that the vertices are concave (bent inwards) for that area enough to put them under the surface. Another similar problem can occur if you have antialaising enabled on your graphics card.

Found the problem. That part of the mesh was uv maped to a black area of the texture and the vertex weight color doesn’t show but it was there. I changed the color of the texture and the uv weight color is now showing. I think this might be a bug.