This issue is documented in Cisco bug ID CSCdw14838.
When creating a subscriber account in the Cisco Unity Administrator by importing an existing Exchange user, the Domain list on the Find and Select Exchange User to Import page is empty. In addition, warnings from the component AvDirSynch_MC appear in the Windows Application Event log every fifteen minutes.
This problem occurs when the global catalog server that Cisco Unity monitors either goes down or has been moved.
Use the following procedure as a workaround for this issue:
Log on to the Cisco Unity server by using an account with rights to modify the registry.
Stop the AvDSGlobalCatalog service.
If you do not have a current backup of the registry, select Registry > Export Registry File, and save the registry settings to a file.
Expand the key HKEY_LOCAL_MACHINE\Software\Active Voice\Directory Connectors.
Right-click DirSynchGlobalCatalog and select Rename to rename the key (for example, DirSynchGlobalCatalogOLD).
Start the service AvDSGlobalCatalog. Restarting AvDSGlobalCatalog should create another instance of the DirSynchGlobalCatalog key with updated information about the new location of the global catalog server.
In the Cisco Unity Administrator, determine whether the Domain list on the Find and Select Exchange User to Import page is being populated.
If the Domain list is being populated, delete the registry key that you renamed in step 6.
On the Cisco Unity server, browse to the location where Cisco Unity is installed (the default is C:\CommServer), and then browse to the TechTools folder.
In the DohPropTest Logon dialog box, leave the Password box empty, and click OK.
On the warning dialog box, click Ignore to start the read-only mode of DohPropTest.
Click GC Monitor to display the Directory Monitor dialog box, and click TotalResync.