I have a crush on this guy-- he signaled me2 come over 2him when we were at a party but didn't talk to me? Y?!?

We were at a frat. He motioned me over to him with the one finger thing, and so I went over there, but when I got there he started talking to one of his brothers?! He's like 3 years older than me... whyyyyy? This has happened multiple times with this guy...