1) make sure the ft item is heated to live animal temps
2) you're not making it any easier by moving him to a feeding tub; all you're accomplishing is adding stress.
3) as Jodan stated, it might be best to make the switch to a live rat before going ft
4) do try leaving the ft overnight
5) I've kept more than 100 snakes over the years and have yet to see one that refused ft
6) don't bother with the chicken broth trick, it doesn't work