Today when i am going to withdraw some steem from my binace wallet for power-up my steemit accoint but it not possible . Binace stop steem withdraw . They stop withdraw and said that withdraw wallet in mantenaince . Without any future notice they just stop client steem wallet withdraw . Why they stop steem withdraw . 
Most likely because they used your steem to power up and vote new witnesses, thus they might have no liquid steem to give you back.
It's true . I know the fact few min ago
It is all so obvious. They have run out of liquid steem. They have powered UP your steem, without even asking you. :) To help a new dictator.
That is why you should just stay away from exchanges (centralized)