A little trick that has worked / still working with two of mine is......

I prescent the room and tubs as usual to let them know that it's feeding time. After the others have fed, the last thing i do before i walk out of the room is take a p/k or f/t rat and shake in front of them a time or two. I then lay it down at the entrance to their hide or in front of them, and walk away. I go back and check the next morning to be sure they ate, and so far, it has been working like a charm.

Good luck!