'groupOfUniqueNames' requires attribute 'uniqueMember'

[Euan Guttridge <EGuttridge@buildonline.com>]

However now when I try to add (via iPlanet Web Server) a new group I am
faced with:

"An error occurred while contacting the LDAP server. 
(Object class violation) 
The directory server could not honor your request because it violates the
schema requirements. Typically, this means that you have not provided a
value for a required field. It could also mean that the schema in the
directory server needs to be updated."

The error in the slapd debug is :

oc_check_required entry (cn=rer,dc=buildonline,dc=com), objectClass "top"
oc_check_required entry (cn=rer,dc=buildonline,dc=com), objectClass
"groupOfUniqueNames"
Entry (cn=rer,dc=buildonline,dc=com): object class 'groupOfUniqueNames'
requires attribute 'uniqueMember'
entry failed schema check: object class 'groupOfUniqueNames' requires
attribute 'uniqueMember'
send_ldap_result: conn=55 op=1 p=2
send_ldap_result: 65::object class 'groupOfUniqueNames' requires attribute
'uniqueMember'
send_ldap_response: msgid=2 tag=105 err=65

Any ideas? Thanks.