thank you very much for this information I just tried it and it worked perfect.
The Bittrex support has send me a second mail in which it says (This issue is currently in the process of being fixed by our development team and should be fixed soon. )
Thanks again I will Edit my post and let the people know about your solution.
Have a nice day and a great weekend :)
RE: Caution Withdraw Issues with STEEM and SBD at Bittrex!!! Edite: Solution found!!! / Interview with the MediChain CEO, Dr. Mark Baker