Unable to verify with Authenticator code

The authenticator will provide different verification codes within a limited time. If the previous code was entered incorrectly or if you cannot type it before the code expires, wait for the current code to cycle through and wait for the next new code. 

If you had an old Authenticator, and the serial code is not the same, this means that the old Authenticator is not the same one that is currently attached to the account. If you have not yet done so attempt to recover your account.