asainsbury wroteYour ldap auth config file has an issue with matching attribute statements, post back the config as a start.
<LDAP>
URL ldap://172.16.20.2
BindDN cn=openvpn,cn=users,dc=int,dc=domain,dc=com
Password p@$$w0rd
Timeout 15
</LDAP>
<Authorization>
BaseDN "cn=users,dc=int,dc=domain,dc=com"
SearchFilter "(&(sAMAccountName=%u))"
</Authorization>