I have a couple that get a little picky. What solved everything for me was temperature. I got this from another thread. Make sure they are really warm when you feed. I would have 4-5 in a cup that thawed, and it would seem when I was getting to the 4 or 5th it would be refused (usually the same snake because I feed in a certain order). Now before I present the F/T I have an extremely hot cup of water from the faucet that I put the mouse in for a couple seconds and present it. Usually it gets taken right away, if it doesn't I heat it up again.
Since using this method I have not had any refused. Hope it helps!