Hatchling feeding

Not a novice to pythons and Boas but I am having some trouble getting 2 hatchings to eat. they are about a month old, one has shed but still not feeding. The snake is still plump from the yolk so I am not stressing it now but I have tried the bag trick, temperatures are good. I have tried FT and Live, Hoppers and rat pups of appropriate size. Any thoughts? another week or two and I might Assist feed them.