Cinema 4D to Unity 3 Bone Problem

I have been using Cinema4D for creating my character and have stumbled upon multiple, closely-related problems in the past. What happened was that when I rigged the character using C4D's joints, everything looked really messed up when imported into Unity. I then found that the rig had to be made out of "bones", so I fixed it and everything seemed ok. . . . I have now spent hours animating, then I import into Unity 3 and: http://img837.imageshack.us/img837/6408/screenshot20101016at621.png

That is in Unity with the error message. This is what it's supposed to look like: http://img543.imageshack.us/img543/6408/screenshot20101016at621.png

I don't understand what is going on at all. MY only guess is that the gun model (to which the "Butt" object belongs) is a child of the "Hip" bone object but isn't a bone or weighted by a bone.

The "Butt" (back end of the gun) is sticking into the character, though I doubt this is the problem.

If anyone could help explain this problem, which might be costing me another few days of work, I would greatly appreciate it.