Even though there are recommended temps out there for basking surfaces, some beardies are just plain picky and don't like it above a certain temp. (My adult mopes and refuses to bask if his basking surface is above 104*F, lol :roll
You could try decreasing the temps by a few degrees to see if your little lady basks then. You can lower her basking spot or raise the lamp to lower temperatures if you don't have a dimmer. Obviously the warmer the better, but as long as it's above 95-98*F which is the temp they need to digest their food, whatever basking surface temperature she decides on should be fine!