Openfire failover problem with openldap

Hi guys, can any one run openfire with openldap and also enable failover for openfire, means if primary openldap server fails to respond then openfire automatically authenticate users with second openldap server. Currenlty i try this and use this in conf

openldap.mydomain.com,openldap2.mydomain.com

But it not works . So please help me regarding this matter.

Thanks

Muzi