What is he thinking(would also like a guy's POV)?

Over the summer this guy i've seen around started saying hi to me. Then a few days later he send me a friend request over myspace. So i messaged him an he stopped replying. At school, he still waves at me. So recently,i tried talking to him again and he stopped replying to me, even though he saw what i said. Yet, he still waves. What's up with that? Why did he send me a freind request in the first place?