A Problem At Work?

[Stephanie S]

There is this older lady at work (she's in her fifties), and she keeps talking about me behind my back in a really mean way. She and I have worked together for eight years, and she does this often. She says things like, "She doesn't work hard" when I am working hard. I am the daughter of the manager of this store. I've talked with the manager, but this lady is a trusted employee, and the manager refuses to believe me. (The manager is my father). She has told this gossip to all of the employees who know me best, and THEY BELIEVE HER!!! So, they treat me really badly by continuing and adding to this gossip. I've tried being overly nice to this lady, but she continues to gossip, and it is driving me crazy!! I wish she would just stop! Can someone help me please?
This lady only picks on me and no one else.