LADIES HELP! When a guy asks you out over email and you chose to not reply, does it mean NO for good?

I asked this girl if she would be interested in meeting up on campus for coffee sometimes but she never replied. She's also on my facebook but we've never spoken in person but were clmates. She would always look at me after I added her on facebook, and I wouldn't know how to reply feeling very akward because at the time I just wanted clroom contacts. From then on everytime we see each other she would stare at me...like just stare eye to eye...little by little I found that I actually like this girl so i asked her for coffee...but she chose to not reply. Does this mean no? I'm soo confused with what is going on in her mind. The signs are there because she would twirl her hair and turn red lately when she notices me walking by.