Quote - Dynamic Cloth simulations only work on the first group created. I tested this with V4 and V4 Summer Fashion. Whether I put the skirt or the top into a 2nd cloth simulation group, the second simulation would not work properly and the object in question would just fall through V4. Putting all dynamic cloth objects into the same (first) simulation group "solved" the problem.

I'll second this. Truly annoying. How can you put multiple cloth objects into the same simulator group?