LDAP Windows 2003

The ldap format that I used to test Windows 2000 servers does not appear to work on Windows 2003 servers. Is anyone successfully using ldap on Win2k3?

What I use on Win2k:

ldap://10.20.30.40/cn=username,cn=users,DC=subdomain,DC=domain,DC=com

The above query would never give me any results, but it worked well enough to make sure that ldap was responding to queries.

This same test on a Win2k3 server gives me the error: Operation Error

Thanks for any advice! Michael