[Owncloud] allow auth only for LDAP/AD users of a specific group

[Vieri]

Hi,

I'd like to only allow users of a specific LDAP/AD group to authenticate.
Group name is VPN and the owncloud settings are as shown below:

"Base DN": cn=vpn,cn=users,dc=domain,dc=org
"User DN": cn=bindUser,cn=users,dc=domain,dc=org
"User List Filter": objectClass=person
"Group Filter": objectClass=group
"Base User Tree": cn=vpn,cn=users,dc=domain,dc=org
"Base Group Tree": cn=users,dc=domain,dc=org

owncloud debug shows:
Debug	user_ldap	getUsers: 0 Users found

I'm attaching an LDAP listing I made with the same bind user as in owncloud but with another LDAP client.
This listing shows the member users of the VPN group.

So how can I modify either owncloud or my AD/LDAP tree in order to allow owncloud logins only for a specific group (eg. VPN)?

Thanks,

Vieri