Yeah, it's all up to the individual snake. I have two adult females that were taking PK(pre-killed) small rats. My biggest girl has snatched up two FT rats now, quite eagerly, while the smaller of the two refused to take the one I tried offering her tonight (first try). She IS rather fussy, tho, and likes her rats to be fresh and totally still before she'll take them. I had her going well on PK and decided to try her out on FT. I'm going to try four weeks, and if after a month she still won't take them I'll just accept that she wants PK.
At least she's on rats...I have three other BPs that I have to try and switch to rats before I try them on FT...what fun.

Just keep trying by offering nothing else for a few weeks. Make sure the thawed prey is really really warmed up right before offering, so they sense that heat. Usually they get hungry enough to try it and then see that it's food and continue taking it. Usually.