I trust that others see signs in his behavior that he already likes you. Additionally, you've tried unsuccessfully to get his attention. Therefore, do something a little unconventional. When he's by himself (or at least with few others), position yourself nearby and cross your arms. Smile big and wait for him to say something to you. I'd also add taking along a bag of Hershey's Kisses and occasionally tossing one his way (yes, AT him playfully if you need to). Eventually, he's going to say something, even if it's, "What are you doing?" Then you can tell him that you've been trying to get his attention for weeks now and just wanted to talk to him, but he's been ignoring you, so you had to go to desperate measures.