Snippet from this IBM Forum:
We are able to query Domino LDAP to retrieve the UserNames, however we cannot see groups. This application requires that a Base DN be specified prior to performing the lookup. It turns out that our groups only appear at the root level of our Domino Server's LDAP tree, not under the O= branch where our users are certified.
This has also been reported to SPR # PPET7X9P82 - Request to all flat names to be returned by ldap search with base DN of c=us