How can I get my ex to pay child support?

It IS against the law for his employer to not cooperate. But everything is a process and it takes time to serve them again and again with papers. I should have received his tax returns last year but didnt. Will I this year?
I have a court order and an open child support case. He has not paid in over 1 year and is doing everything he can to avoid the child support agencies attempts at collecting from him. Even his employer is not cooperating with child support. How can I get him to support his child?