since I deposited some BNC to Hitbtc and wasnt credit to my balance. also a friend tried to deposit and got the same problem.
I can tell you where your first mistake is ... but I'm pretty sure you already know 
Well I was thinking it was about Payment ID but it was ok, so I dosnt know if I need generate a new payment ID for each deposit.
Did you use Bytecoin Wallet to send your money to exchanges or did you only use the exchanges?
If you only used the exchanges, then you better write to their support.
If you only used the exchanges, then you better write to their support.
I withdraw directly from the pool to the exchange address (wasnt my first withdrawal, the first was credited correctly)
Already contacted pool/exchange support