ldap_add: Critical extension is unavailable (12) adding users to posixGroup

[Douglas J Hunley]

I'm trying to use the output of slapcat from a RHEL3 machine as the input to 
ldapadd on a RHEL4 machine, but it keeps blowing up with:
ldap_add: Critical extension is unavailable (12)
        additional info: context csn update failed
when trying to add users to the memberlist for a posixGroup

This particular group is about 33% of the way through the input file (an 
admittedly large input file (for us anyway)). 

I'm using:
[root at server ~]# rpm -q -a|grep ldap
nss_ldap-226-18
openldap-clients-2.2.13-7.4E
openldap-2.2.13-7.4E
openldap-servers-2.2.13-7.4E

I'm using RHEL4 U5

The OS has all outstanding updates applied.

I'm initializing the LDAP db with:
dn: dc=customer,dc=com
dc: customer
objectClass: top
objectClass: domain

dn: ou=Users,dc=customer,dc=com
ou: Users
objectClass: organizationalUnit

dn: ou=Groups,dc=customer,dc=com
ou: Groups
objectClass: organizationalUnit

dn: cn=cust,ou=Groups,dc=customer,dc=com
cn: cust
objectClass: posixGroup
gidNumber: 30000

The group it fails on is trying to add 9294 users. I can send the input file 
if requested (it's large)

Any ideas why it's blowing up?
-- 
Douglas J Hunley