Why is he avoiding me? 10 points to simplest answer?

So this dude is 2 years older than me the past months he is being staring at me trying to talk to me showing signs that he likes me even my friends told me that. But friday at school he was flirting with many girls like he was talking to them and his body would look directly at their direction and stuff. So i went up and talked to him at some point i asked him something not only he answered me something else and than answered nothing he was ignoring me and trying to avoid me? Why did he did that??