Hmmm. It's hard to say as there's a number of different things that can go wrong, but here's where I'd start:
- make sure the figure you are trying to match is in a zeroed pose before you start. ie. your underlying figure model in AC3D should look EXACTLY like the model in the poser setup room
- make sure all your figure IK chains are turned off before you start (both on your clothing and the figure you are trying to conform to)
- make sure all the group\bone names match EXACTLY. note that the name on the parameter dial might not match the internal name... you'll need to look at the second name in the properties tab of the parameter dial to make sure you have it named correctly. i.e. lShldr not lShoulder. Some of them are spelled out in the channel list, but not inside the actual model.
- make sure all your joint centers and rotation orders match. ditto for the hierarchy.
Note: sometimes it's easier to just swipe the skeleton off the figure and delete the bones you don't need than it is to try to get things lined up. Take the clothing into the setup room, then double click the figure in the library and it will load up the figure's skeleton onto your clothes. Delete the bones you don't want, then build your groups after you are already in the setup room. DO NOT LEAVE THE SETUP ROOM until it quits barking about ungrouped faces. If you try to leave early and continue later, it seems to mess it up for some reason. Using the existing skeleton is a *much* easier way to do it than trying to rebuild one, especially since it needs to be an exact match anyway.
Don't know if you've seen it already, but if not, this tutorial on Smith Micro's site is pretty good:
http://my.smithmicro.com/tutorials/1643.html