Mariah Carey: Baffled By Cannon Beef ... He's Always Had Access to the Twins

Mariah Carey doesn't know what the hell Nick Cannon is ranting about in his angry rap about child custody and divorce ... sources connected to the singer tell TMZ.

Nick released the song Thursday, in which he says, "And now I can't see my kids 'cause the government sucks," and "It's f***** up that the time you spend with your own kids is called visitation."

Our sources insist Mariah and Nick have gotten along extremely well, especially in the child custody department. They say Mariah has never denied Nick access to the twins and Nick has always been able to see them when he wanted.

As for why Nick has not signed the divorce papers for nearly 2 years, our Mariah sources believe that Nick is being manipulated by his lawyers, because the sources say there's no beef between Mimi and Nick.

Nick raps, "It's been 2 years and I'm the one that's been waiting." It appears he's talking about getting divorced, but we're told Mariah and her lawyer have been pressing Nick to sign the docs for months and months, but he's been stalling.