Definitely a welding issue, if I may stick my neck out here (LOL). Poser needs the vertices which are to be welded to be in exactly identical positions, down to the last decimal point. Sometimes inaccuracies in the modeller's export routines (due to Poser's titchy scale) can round the coordinates up or down. The easiest way to achieve this, by the way, is to have a continuous mesh; but some modellers think that if you want groups, they have to be separate items and they duplicate the vertices along the border. Second, there needs to be an actual weld statement in the CR2 - hand editing can sometimes lose that line of code. I hope that made sense - if not, let us know how you did the grouping and the rigging.