My crush doesn't seem to acknowledge my presence; what should I do?

So I recently realized that my current crush never acknowledges me when I'm talking with a group. For example: Just today I was standing with two other people (both which she knows) and she walked up. When she started to speak, her body language gave off that she was talking to them only. Never did she once even look at me.

It's not that she doesn't know me. We've roomed together for a week on a trip with the school's band... Am I doing something wrong? Or does she truly dislike me? (If she does, then why did she friend request me first on Facebook?)

TL;DR: Her body language shows that she's speaking to everyone in a group except for me, even when there's only two other people. We're acquainted, she friend requested me first on Facebook... Am I doing something wrong or does she just dislike me?