I'm guessing that like most breeders, the one who sold you your little girl keeps the babies in a hatchling rack. So, your baby is used to being in a six quart tub. The enclosure you have there is way too big and open; that much space will stress out a baby and throw it off food.
If you can't do the six quart tub setup Deb suggested, then you really need to clutter up the one you have to make the baby feel more secure. You can use loosely crumpled newspaper, fake plastic plants, more hides - anything to take up all that open space.
At her size I doubt the breeder had managed to switch her over to f/t feeders yet. So, try a live mouse hopper or a rat pup. I would try the pup first - a hopper will run all over that huge tub! Just leave the live rat pup outside whatever hide your baby is using at that time, close the enclosure or put it back in the rack, and walk away for a while.
After she's taken a few live rat pups you can switch to f/t.
