Issue using OpenVpn with LDAP win2k12 based

[tbaror]

Hello,

I am trying to setup users vpn with Open vpn Pfsense 2.4.1 using authentication with ldap based wind2k12 r2  , i have active directory that divided to OU's geographical location based that have its users OU relted to its location and we have on same geographical OU named "SecurityAccess" with users group named "SingUsersVpnAccess" that we want to give that location based on it group membership access to the vpn as shown in image below.
I have already set in the past Pfsense with OpenVpn active directory  authentication based but with much more small scale Acetive directory and pointed to the ou containing the users and ou with cn containing the group membership and its working .
in the following i get error ,

/openvpn.auth-user.php: ERROR! Either LDAP search failed, or multiple users were found.
user 'username' could not authenticate.

Any suggestion how to set this ldap ?would be great
Thanks