Have you ever spoken to him?
Have you ever seen him looking at you?
How old are the two of you?
What makes a man's "hunting" instinct kick in is to see something that other people want, and to see something that he cannot have. You have to make yourself seem attractive or irresistible to other men in the room. Talk, laugh, flirt, look people in the eye, and most of all tell yourself that you are the most attractive thing in the room, and believe it. When you walk to the ladies room or another area, walk with your head held high, as if you don't need anyone in this room, as if you're thinking of something so important. When you see him, look him dead in the eye, hold it for the count of five and look away and start talking to someone else. If he's there, use any excuse to be able to walk as close past him as you can. When you walk past, don't look at him, the next time, do look at him, mix it up so he never knows what to expect from you.
Men are attracted to women who are sure of themselves, that know how to have a good time, that smiles and laughs. You can't force something if it's not there, but if there is the slightest bit there, you can bring it out by allowing your personality to flower, looking him in the eye (which is kind of a challenge), and pretending that he doesn't exist.
I welcome your thoughts, let me know if you want to talk more
I do wish you luck. :) Feel free to come back and let me know how it goes.