No matter what bait we use, the rats will trip the trap and eat the bait off, I think we have caught one once. We have tried all the advice about trap placement, and baits, nothing works, we just keep feeding them. Wish we could figure it out. I imagine them throwing stuff at the traps to set them off.
We use a similar set up for chipmunk, we put the trap in a small bucket so they have to hop in to get stuff, hate doing it but they keep hiding all my corn and sunflower seeds every where, and they drive the dogs nuts, which drives me nuts.