HA Active Directory for F5 authentication

I have two f5 Big-IP wit LTM module in HA. I have configured Admin authentication in BIG-IP through Remote Active Directory and It works properly.

The challenge is I have several synchronized AD servers and I would like to achieve HA in Big-IP authentication.

I have created a pool with my AD servers with a custom LDAP monitor and It seems that works because all members look up in the pool. I also created a virtual server that listen in port 389 and use the AD server pool as default pool. However, when I set the host value to virtual server IP in system-->users-->authentication, all authentication attempts fail.

Is required an special configuration in virtual server to make it work?