exporting rigged object problems

Hi, I have been playing with blender for a few months now, and I have all the basics down. I am able to create a full scene (mapped, and animated). I ran into a problem a few days ago that I have not been able to shake. I ran a search on a few forums and cant seem to find what I am looking for. I have a model that I exported in .x format and the export was perfect! no deformations, uv map was applied correctly, ect. So i went to the next step. I rigged it, set up an animation. (simple walk sequence). as far as I can tell all the vertices are attached to a bone. When I try to export though, i get an error message that says the following:

AttributeError: ‘NoneType’ object has no attribute ‘getData’

If anyone can just point me in the right direction here it would be deeply apprechiated. thanks