Can't log in

Hello, so i made the change to the realmlist to my MOP client i got from old Molten (i used to be able lo log with the old realmlist), i can log to warmane but i can't log ingame it shows the "must create battle.net account" error message, any help please?

Checkout this guide and make sure your realmlist is up to date. Also, if you are playing MOP, make sure you have the 5.4.8 version since we recently upgraded from 5.4.2 to 5.4.8.