First, I agree with all of the above answers. Second (in addition), Are you feeding the same kind of rodent that he was raised on? Mice & rats smell & taste different, & many BPs will only accept the one they like best. (This is not true of many other kinds of snakes, but it's fairly typical for BPs to show a preference.) Also: when your snake is fairly new to you, it's best to feed the same way as what was previously successful; that is to say, if he was raised on live, he's likely to want live, & if he was raised on f/t, then only offer f/t. BPs are pretty "opinionated" about their prey.