I am trying to setup sshd to allow logins only for a specific group.

I have added the following to the sshd_config file and restarted sshd.

eDirNameContext context.users
AllowGroups sshgroup.context.users

However, the sshd log says :
10 Apr - 11:25:58[0020534579]  <1> : getgrouplist: groups list too small
10 Apr - 11:25:58[0020534579]  <1> : User <user> not allowed because not in any group
10 Apr - 11:25:58[0020534579]  <1> : input_userauth_request: illegal user <user>
I have tried several variations on the groupname:
just the groupname
ldap long (cn=sshgroup,ou=context,o=users)
dotted ldap (as in the example)
I can't get it to work.

Any ideas?