Since burnout shirts themselves can be a little problematic due to the fact that there is not a lot of fabric in some places, getting rhinestones to adhere can be tricky. Are you sure the press is at the right temp? I don't mean the readout, I mean is the platen the right temp. Either get a heat test kit from a supplier or get one of those guns from the auto store that measures heat. If the platen is not the right temp, then you may not be melting the glue. What kind of transfer are you putting on the shirt? That can have bearing.