SharePoint 2010 - New synchronisation connection 'pending'

Hi,

I'm trying to configure a connection to a directory service server to import users.  

Type: Active Directory
Forest Name: XXXX
Specify a domain controller: XXXX
Windows Authenticaton
Account Name: XXX\SPSync
Password xxxxxx

When I hit the Populate Containers button it seems to hang on 'Pending'

The UPS service is running OK, FIM services are both running.

Any suggesstions would be appreciated.