Importing a specific AD group into SharePoint 07 (via LDAP)

I have a complex 2003 AD structure implemented.

I need to import a specific OU of users into SharePoint 07 using the inbuilt SharePoint user profile tool based on LDAP.

In SharePoint under Search Base and User Filter I have tried all types of combinations for the DN but nothing works and it errors.

Will SharePoint only read a string of a certain length, my user OU is 3 levels down in the overall structure? so the DN is fairly lengthy, could be confusing it?