centos 5.x and ldap failover

I am having trouble with LDAP authentication fail-over. We currently have two CentOS-DS directory servers working in a multi-master setup. One Server per site. Normally, logins process fine. However, I am having trouble with the fail-over part. if ldap_SiteA.domain.local goes down, all the servers in that location, that normally point to that first, do not then look at the second entry: ldap_siteB.domain.local.

We use ldap for both logins and Sudo. Here is a copy of my /etc/ldap.conf on a CentOS 5.6 server running in Site A. (for site B, the order of servers is reversed)

Here is part of the script I wrote up to do the authentication via LDAP:

authconfig --enableldap --enableldapauth --enablemkhomedir --ldapserver=ldap_siteA.domain.local,ldap_siteB.domain.local --ldapbasedn="dc=domain,dc=local" --update
echo 'sudoers:    files ldap' >> /etc/nsswitch.conf
echo 'base dc=domain,dc=local
timelimit 15
bind_policy soft
bind_timelimit 30
idle_timelimit 30
uri ldaps://ldap_siteA.domain.local/ 
uri ldaps://ldap_siteB.domain.local/
ssl yes
tls_checkpeer no
pam_password clear
#debug used for troubleshooting
#sudoers_debug 2
sudoers_base    ou=SUDOers,dc=domain,dc=local
' > /etc/ldap.conf

Am I missing something for fail-over to work properly? also, we seem to have a few hosts that like to fire off LOTS AND LOTS of connections to the ldap server. Should I adjust my timeouts better for that? use the NSCD service? both?

Thanks!