In that skirt above (and in lots of others that I've seen for Vicki) there are no buttock parts - the grouping goes straight from hip to lThigh / rThigh (sounds like a diet, doesn't it? ;-) ). I've had trouble making things work with buttock parts in there, they never seem to bend properly; but I can't explain why it works better without them either. Hell, I'm new at this myself. It seems to go against the rules, but as I say, it's not just me doing it.