C-CEX is a scam exchange. They did not update their BTCZ wallet when the Zhash algo fork has happened.
So the coin what is listed on C-CEX is not BitcoinZ anymore, if you try to withdraw (or deposit) BTCZ from that exchange to the actual wallet you will loose the whole amount because it is not compatible with the actual blockchain.

Because they are not willing to cooperate with the BitcoinZ Community, the best is to avoid totally them, otherwise you will loose your money.