Some snakes don't like frozen thawed and have to be "trained" to take it. Have you tried shaking it while holding it with tongs?
Up here live is more expensive than frozen thawed so I wanted to put my ball python on it as soon as possible but he wouldn't eat it as a hatchling so he had to get started on live.
Basically what I did was start feeding him live in a separate feeding tub. He got so used to eating in the tub anything that moved in their was food. So he took frozen thawed easily when I "zombie" danced it and then I started feeding him frozen thawed in his living tub. Sometimes he will take it if it is left over night, but often I need to twitch it for him.
My baby blood eats them over night when I leave them in his tub.
I also wash of my Rodent Pro rats from Petco because often they are bloody and packaged with feces or urine and my snakes seem to not like that.