^ That
To add, here's some other things you can try:
~ Get your thawed feeder, crack open your snake's tub a hair, and with a hairdryer heat up the feeder but with the air pointed towards the tub (I put the feeder in my palm and hold it near the tub and heat it there). That way you're blowing all that tastey hot rat/mice stink towards and into the tub and that might make him more interested and perky. Usually mine will take it within seconds of putting it in the tub with this method since they already have a ton of the smell wafting around.
~ For the more shy feeder (like one of my balls) I stick her inside her hide if she's not already in it and put the warmed thawed feeder directly in front of the entrance to her hide. That way if she needs to move in the night (I only feed this one at night) she needs to move right over the feeder and she takes it everytime (perhaps she likes dinner in "bed"? I'm assuming she feels more comfortable when she can eat right in/near her hide). I would put the feeder on the warm side over the cold. Cover the tub as Mike said as well.
Hope you have success!