I try to migrate from Exchange server to zimbra.When I add one user to ldap on zimbra,or use this command ldapadd -f /tmp/posixusers.ldif -x -H ldapi:/// -D cn=config -W
ı always get this message ldap_bind: Can't contact LDAP server (-1).

Does anyone help me?

I use this article UNIX and Windows Accounts in Zimbra LDAP and Zimbra Admin UI 6.0 - Zimbra :: Wiki

Thnak you..