Are you using a 4 foot tank for a BP? That's way bigger than you would ever need or want for a ball python. They like small tight spaces, honestly. They live most of their lives underground in the wild so having a lot of open space just freaks them out and can cause them to stop eating and not properly thermoregulate which can cause health issues. I'd rethink the 4 foot tank, you're never really going to be able to control the temps and the humidity properly in something like that.