This was probably the problem of someone I know a week ago. He said to check what's happening to Yobit since he uses it as an exchanger so I did was to check their Twitter account and only read something about a maintenance, didn't thought that it was a serious problem as I haven't heard from him again. You need to ask around for a good exchanger first before investing your money if you want to trade. Topping the list lately was Binance and Bittrex. There's Etherdelta too who is making a name as it is dedicated to ICOs that some experts considers as "garbage coins" 
I do mainly use coinbase and Binance; however, they don’t have all the coins that I want to invest. I wish there an exchange which can include all coins.
the problem is nowdays big exchange take a high fee for liating new coin.even small exchange like cryptopia and coinexchange charge 2 until 3 btc for listing new coin.
if u wanna trade better use credible exchange like bittrex,binance or poloniex.they also have so many coin listed
