[Q] Calling with blackscreen. topic

Hello i'm new here but i got a small problem and i want know if us can help me.

I'll try explain that cuz my english so bad.

I got a samsung S3 i9300 and installed a custom rom cyanogem 10.2.0 - stable.
but...
When I make a call the screen goes black, I shield and speak without calling problems that ends the call back normal screen.

any1 already sloved it?
any1 already see that?
any1 can help me?