Find mailing list memember on ldap query

Hi Folks,
I try to get the members of our Univention Mailinglists via ldap - but it seems I face some strange behavior.

When using Apache Directory Studio I can vbrowse the entire directory and get all entries.

Now I tried to automate things using php ldap but I do not get the mailinglists… even though using base (dc=domain,dc=de’) and (objectClass=*) does not provide any result.

what’s wrong?!