O.P. - There are probably a hundred women on your campus who would have jumped at the opportunity to be with you so don't let this get you down.  I agree with JAM and James's advice.  Actually, if you ignore her a little, it might pique her interest.  You don't have to be rude, but you know the routine.  For example, let her see you talking to another woman and give her a nonchalant, "Hey, how are you?"  She might wonder, "What's going on with them?"  A few days later ask her out again the way James described.  AHH the games we play.  
 
James - I might have to give you the rest of my number now.  I might like a cup of something hot later tonight.