FreeBSD + Apache + PHP + horde + imp + Exchange

[A. David Perez Marfil]

Hi list,
i am new with imp and horde,
i have a FreeBSD box with apache and php installed,
and from the file test.php everything looks ok,
but i got this message from the script trying to access...
-------------
Warning: LDAP: Unable to bind to server: Invalid credentials in
/usr/local/phplib/ct_ldap.inc on line 30
Session_ldap failed: LDAP bind failed
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how should i setup this file to work with an exchange server?
thanks
David Perez