Well, you could try switching him to live rat pinks / fuzzies before attempting to switch 2 things at once (frozen and rat transition)
If he gets used to the live rat, after a few good feedings then try the f/t again. Or, try a f/t mouse, and once you get him on those then do the rat swap?
I don't have any secrets personally...my girl is a piggie. But perhaps the change of 2 aspects is too much for him.
Also, could try blasting the f/t head with a blow dryer right before dance.
My girl shoots out of her hide like she hasn't eaten in months when she hears the hair dryer lol.