Do you have a link to where they said there no story? I've seen Cosby's lawyer claim that, but I've seen no statement from them that there was no story.
What I've seen is that she originally told one story, hinted that she'd covered up the truth on Howard Stern because HarperCollins was afraid of getting sued, and that when the other women came forward she was emboldened to finally tell the truth. That's definitely changing her story, but it's more consistent than Cosby's camp is trying to paint it.