Postfix working with Ldap

Hi everybody,
I am working on mail server(postfix+dovecot+amavisd-new) working with ldap directory. I have an error while attempting to send a mail on my own mail address in the domain:

Jul 28 12:04:14 HA1UB postfix/smtpd[1482]: warning: dict_ldap_lookup: /etc/postfix/ldap-aliases.cf: Search base 'dc=ub,dc=edu,dc=bi' not found: 32: No such object

I think is that my ldap server is on another server which is not hosting my server mail and the search base isn't interpreted by the ldap server.

Can you please advice what can be the search base.
I am just try to make a mail server based on ldap and I am newbie in this domain.

Thank you in advance.

Eloge