Try putting a hide box also on the cool side and she will go where she feels comfortable.
My Ozzy I keep warm side about 90-92 and cool side about 77-82 with night time temps at about 85 warm side to 75 cool side.
Ozzy stays pretty much in hide on cool side which is more toward the middle of cage. I have him in a 20 gal glass tank with screen lid.
What are your humditiy levels??