Go to Organization Configuration in EMC. Right click it in EMC and select Modify Configuration Domain Controller. Point it to your DC hosting the PDC
After that restart the Microsoft Exchange System Attendant services on the mailbox server.
The Microsoft Exchange System Attendant Service does the following thing:
Forwards directory lookups to a global catalog server for legacy Outlook clients, generates e-mail addresses and offline address books, updates free/busy information for legacy clients, and maintains permissions and group memberships for the server. If this service is disabled, any services that explicitly depend on it will fail to start.