Yobit is scam exchange.
They always use different theory to scam people by ico ieo freecoins airdrop etc.
First they let you earn small and as soon as you deposit big and they scam you without you realize.
When you realize you scammed then it's too late.
I advice do not let them steal your hard earned money.
If you have funds with yobit withdraw as soon as possible this exchange may go away anytime and they do not publish admin information not even whitepaper.
Do not leave your funds at yobit or else you will loose all sooner or later and you can do nothing after that.
They stole my 2.1BTC and I could do nothing.
Be quick withdraw all else loose all.