I'm hearing a lot of bad things about Poloniex recently.
I even read an article recently about Poloniex holding 28 million in uncredited deposits.
My few words of advise are stop using Poloniex and start using Tradeqwik.
Tradeqwik is a relatively new exchange with under a thousand customers as we speak but it's the exchange I use to change my Steem to Bitcoin.
Why?
Because it's fast to use, they have great customer service, the team behind it are all friendly and are active users of Steemit.
Not only this but the plans they have will transform this exchange into one of the best out there with some great innovations not yet seen.
The 
Tradeqwik has a great asset you can buy called TQS with which you can earn your share of 20% of all trading fees collected. These are paid out weekly in the currency they were collected in and are planned to be paid out daily in the future.
So support and use Tradeqwik as your exchange to convert your Steem.