why doesn't my boss like me?

I don't get it! I do my work, I always speak to her, I dress clean and professional, smell good and my hair is always done and neat. Most people around the office think I am so sweet. I always go beyond the call of duty and do more than most of my co-workers who she favors over me. I just don't get it! What am I doing wrong? What can I do differently? She has not harassed me or anything, but Iothers have noticed that she is not particularly warm toward me. In addition, she barely speaks to me, she sparks up conversations with everyone besides me, and she still has not completed my evaluation! I have tried to consult her on some of my work, spark up conversation, and I bought her a very nice gift from my vacation, but she is still very dry toward me. I don't know. . . . .