How long have you had her? How old is she? Did she come with a feeding record? *Are you SURE she was fed rats previously?* If she was fed mice, under-
stand that they smell & (presumably) taste far different from rats, & many snakes take some time to "convince". Have you ever offered her a f/t hopper mouse?
She sounds hungry, but yes, turned off & afraid of the rat smell. Try mice...or other...