I use candy melts alot. Usually if I run into problems it's related to temperature. If the chocolate is not the right temp when you mold(for me usually too cool) it will get a white film on it when it sets up. Also if you overheat the chocolate it will sieze up and crumble like it does when exposed to water. I also found that the cheaper brand that they sell in craft stores doesn't melt as nice or taste as good as Mercken's or Wilbur's.
HTH
HTH







