Friendless in 6th grade, hated by everybody.?

I am 12 years old and I am hated for an unknown reason at school. Whenever I try to sit by someone at the lunch table, they move away to a different table. And when i'm at recess, i am all alone. Can anybody name any possible reasons why or how i can make a friend? (I do also take a social skills cl, but it doesn't help)