Rnbowjester76- Do you have a temp gun or something to check temps on the warm and cool ends of the tubs?
I believe BPs need a warm temp of 90 on the hot end and 80 on the cool end. If they are too cool, they won't eat. Also what is the room temp they are in? I've heard that you need to keep the room temp around 75 or higher to ensure the temp on the cool end of the tubs is warm enough.

I don't have a rack setup yet and only 1BP, so I'm not an expert (I have other species though). But I think if you increase your warm end temp it should help.