LDAP Groups and Mac OS X

Hi,

I'm trying since a full week now to make LDAP Groups works for Apple Mac OS X Server (TIger - 10.4.9) but I really cannot make it work at all.
I checked the third checkbox into the module administration page and put "cn=Groups,dc=ServerName,dc=DomaineName,dc=fr" into "Nodes containing groups:", put "memberUid" into "Attribute holding group members:".
I never get Groups' name when I log with a user name availlable into the LDAP Directory. I succesfully get the user and auth is OK but groups never create any roles.
I suppose if a user is a member of several groups I should get all those groups and have several roles created ?

Also I'm a little bit confused, Apple Workgroup Manager, used to create users on the server, allow several login name for each users. I always create several ones for each users but how can I get those users correctly mapped to one user when login into Drupal ? I get one new user each time I log into Drupal instead of having them mapped to the right user ?