Sent Etherum but transaction still not confirmed

Basically, I sent a transaction from Exchange (A) to Binance, it was based on Ethereum. Earlier I made 2 transaction and they went smoothly. The third time I did exactly the same stuff I did last time and I still haven't received it. "Sorry, we are unable to locate this Transaction Hash" I have been waiting for more than 6 hours now.

This is now the second time it has happened WTF is wrong ?

Any one ever faced it ? I have written to Cex.io's support so far no response. Am not sure what do now.