Yobit is a scam they keep their Wallets on maintenance indefinitely and will not allow you to withdraw their old coins. I have been trying to withdraw my OMG coins without any luck for over 6 weeks now they don't respond to any of their support tickets or telegram Channel
I have been listening for more than a year and a half that yobit users have problem with that exchange and their wallets.
And still every day someone come and use yobit without reading anything other people say and all warnings.
Don't use that exchange, just don't.