Income certificate

Income certificate like what? I'm an independent distributor of one company... i had many many requirements i had complete requirements and id and supporting documents. Is that still not enough?. What things i need to do? Maybe i just get a one agent can do my visa. I'm already very tired do it. I don't know what things i need to do.
My one friend already go china. She just pay one agent and agent do all for her application. So much better i do this. My one friend have no boyfriend in PRC but she can got entry permit.. how about me. I will go there with my boyfriend but i can't got the entry permit? Is that very unfair.