Re-request Buddies after new Openfire Server

Hi

We were setting on a new virtual Openfire Server on Debian with LDAP. We importet the certificates from our old Openfire Server an everything works like it should. The problem is:

we are using pidgin as our xmpp client. After setting on the new Openfire Server the users can see their old buddies but they have to send a re-request for authorization.

What can we do against that?