My Epoxy Hates Me :(

So, I'm in the process of making several pendants for an upcoming arts & crafts festival and am filling the bezels with a two part epoxy. Usually an easy thing to do except, for some reason, this epoxy hates me. I've had to throw out an entire batch of pendants because they wouldn't cure and am praying that the coaster I'm working on doesn't do the same. I want to get at least a set of 4 coasters finished to use as a 'bar-warming' gift for some friends who just finished building a wet bar in their home. If I continue to have epoxy issues, though, that might not happen. Grrrrr.