Did you get her from a breeder? If so, the breeder should have fed her a few times before they sold her. My thought would be to feed what the breeder had fed her. Their are many reasons why BP's dont feed... New home, high traffic, light at night, shedding... the list goes on and on.
Their are a lot of opinions about feeding live, P/K (pre killed), F/T (frozen thawed). It really comes down to what is good for you and your BP.
Another thought, is that if the breeder fed her rats, and you are feeding her mice, she may not take because its different than what she's used to eating. She also may be used to eating P/K or F/T, and live just didnt agree with her... BP's can be picky eaters sometimes, and is never an exact science.
I'm sure other folks here will be able to help more...
Good Luck!