[Samba] rc3 net groupmap add fails

[godber at win.co.nz]

Relevant part of "net3 groupmap list" is

System Operators (S-1-5-21-1617713866-2789119093-1479812082-1007) -> sys

In howto there is the following example 

net groupmap modify ntgroup="System Operators" unixgroup=sys
net groupmap modify ntgroup="Power Users" unixgroup=sys

You can add System Operators but trying to add Power Users fails.  If you do it in reverse adding Poer Users works.

net groupmap add ntgroup="Power Users" unixgroup=sys
No rid or sid specified, choosing algorithmic mapping
[2003/09/09 18:22:39, 0] passdb/pdb_ldap.c:ldapsam_add_group_mapping_entry(1911)
  Group 3 already exists in LDAP
adding entry for group Power Users failed!

Is the example wrong?
Can multiple ntgroups map to a single unix group?

Also

net groupmap add ntgroup="Users" unixgroup=users 

fails other unixgroups work is users special

users is a group in ldap 

ldapsearch -LL -H ldap://localhost -b"dc=hattaways,dc=com" -x "(cn=users)"
version: 1

dn: cn=users,ou=Group,dc=hattaways,dc=com
objectClass: posixGroup
objectClass: top
cn: users
gidNumber: 10501
memberUid: godfrey



Otherwise rc3 appears to work

Many Thanks

Godfrey