There are three possible reasons for that.
1. Password on your account had been reset.
In case someone gains the access to your email account, he will be able to reset your HitBTC password and get the access to it as well. To maintain high security level on HitBTC, once you initiate the password recovery request and successfully confirm it, the withdrawals on your account will be kept on hold for the next 72 hours. You will see the proper notification in your Account section.
In case you haven't asked for password recovery, please contact our support team as soon as possible.
2. Check the status of the currency.
You may face this problem in case when a currency is on maintainance. Please check System Health page for more information.
If you didn't find what you were looking for, please contact us using this form.
3. You are trying to withdraw ETH token to another HitBTC account
It is impossible to withdraw Ethereum tokens to a HitBTC address from your account. If you try to do so, you will see "Currency operations not available" error. It does not mean that withdrawals of this token are suspended.
Please try once again but input an external wallet address for your transaction.