Did you have that domain added before the migration? If so could you please ping the domain, that would tell us if you are directed to the new server or the old server?
If you didn't have it added before the migration, please verify that you did login to the premium account (details should be included in the welcome email you got) and added it. If you did login with the old details the domain would have been set for the old server.
Also, since you now have a premium account, using the ticket system in the clients area would be recommended as that would be where you access the premium hosting support, not all that browse these forums have access to the premium accounts.