Are you two already friends, and you’re trying to slip into a more intimate relationship?
Or do you two see each other in class or something, but not really interact much?
What’s your age range?
As an uber shy guy myself, I find in the classroom settings I am extremely uncomfortable, and I lose my “bearings” so to speak. Any kind of subtlety is completely lost on me because I’m not in my environment.
If this is your situation, you might want to try to get in contact with him outside of the classroom setting. Or be more blatant about your interest in him.
If you’re in the “friends” situation already and want to get closer with him, what kind of social situations are these? do you hang out in big groups of like 15 people? Do you hang out with 5–6 friends? Are you two ever together, without other people?
Large groups are a bit intimidating to me, I always find myself retreating into my mental shell and mostly being an observer in the situations. On top of that, I tend to typically assume people are joking around. I joke around with plenty of my guy friends (to whom I am not attracted, just to be clear) with flirtation, because the awkward reactions you can get are funny.
If this is the situation, make sure you’re continuing your sign of interest as the group size dwindles down. Make sure he realizes you’re serious, and not just doing it because it’s funny.
All in all, try to make sure your intentions are more clear.
When I was in high school, it took about 6 months of flirting for me to realize that the girl was actually interested in me. It took me until one of the nights that everyone else had gone home and it was just us two hanging out. It took me until she continued the flirting with no observers around, to realize that she was actually interested.