Another option would be to cover 75% or so of the screen top with tin foil. I had lots of success with that when I used aquariums. On top of the tin foil, I used black duct tape to make it look nice . When doing this, you just want to make sure the snake can't come into contact with any of the sticky parts of the tape. There was a link that showed how to do this on here, but I can't find it. Perhaps someone else can post it? Once I got the humidity stable, I added a water dish with a larger surface area to raise the humidity up that extra 10% or so when they were in shed.

Another thing, when you offer your snake food, you want to do it once a week. If it doesn't take it within about 20 minutes, it probably isn't going to. Take it away and wait another week before trying again. When you try to feed her every day or every two or three days, you are probably stressing her out. Just be patient with it and make sure you have adequite hides and temp/humidity conditions. She could still be acclimating herself to her new home. Until she starts eating on a regular basis, keep handling to an absolute minimum.

If she is soaking a lot in her water bowl, I would look her over to make sure she doesn't have mites also.

Hope that helps a little.