HELp..this girl>?..but she?..?

So I asked this girl if she ever had a crush on me. I thought she seriously did but she turned me down in the nicest way possible. She told me the things she liked about me, my eyes, smile etc but she never had a crush on me so I was like ok cool. Well I asked her if it was cool if we can still be friends then and she said yeah that would be awsome so I was like ok cool. Well now she ignores me when I write her. I say hey sup..to her and she ignores my messeges pretty much. Why would a girl do this? I dont understand why she said its cool to be friends but we dont talk, makes no senese feels like she is dead weight to me now cause we use to talk but we dont now.