I don't understand why they don't like me. I'm emo and skater, on top of that i'm nice, or do they just not like me cuz i'm nice?

It's probably because you call them "emo skater guys." Labels are lame, avoid them at all costs. You sound like me when I was younger, I was one of the guys. They probably won't look at you in that way because they see you as one of them.

Maybe its because you dont dress like they do.
(this doesnt mean that you have to dress like a boy everyday)