Try taking the frag out of water and applying the glue to it, then you dunk the frag in the water and the gluw should go kind of white, dip it a couple more times and then stick it to the rock and wiggle it a little to get the glue to attach, then hold it in place for about 15 seconds, it should hold fast. After gluing a couple hundred frags and spending a couple months with your fingers covered in glue you start to develop a technique, but its individual to everyone, I am just giving you mine.