Hi. Well, while not quite the right place for this particular question, I do think I have the answer:

The problem is most likely in how many polys you assign to a group vs. how many polys are in the mode itself.  

So, if we can see a wire of that same model, I'd hazzard that you didn't allow many polys in one area or the other.

If this turns out to not be the problem, than the answer is more likely the joint zones. That's simple enough and complex at the same time. Just make the joint zones visible and then adjust the red lines so that they don't extend beyond the boundary of group they're for.  If you try both things and still have trouble, post here and I'll move your thread to the Poser forum for ya.