Hmm, do you have the tank back and BOTH sides covered and insulated? When glass tanks are uncovered, BPs especially don't feel very secure and start looking around for safer spots. Also, you should make sure she has two identical hides, one for each end, so she doesn't have to choose security over temps.
Also, the foil treatment for a screen top is really easy and cheap. I believe they made a sticky of my picture tutorial in the Caging Forum.