Are there hides at both ends in there? I can't tell by the picture. If not your baby might not feel secure. It's a big, open clear tank and a little baby snake. If it's really big, you might even want to put some ground cover, like more fake plants.

It could also take your baby longer than a week to settle in, OR some snakes just aren't interested in f/t. A lot of things could be going on here. Did you tried to re-animate the mouse? When I fed my instructor's snakes a few years ago, the ones that ate f/t I was taught to hold the tail with tongs and "wiggle" the feeder some to give it the appearance of movement. The snakes showed a lot more interest afterwards, as opposed to just heated alone,