Problem with ldap_connect()...

[celvane]

I'm having a serious issue with ldap_connect. I have another server on which this code works, but it's a Windows box.

PHP script (ad_test.php):

$ad_server = "fqdn.ad.forest";
$ds_port = 389;
$ad_conn = ldap_connect($ad_server, $ds_port); 
echo ldap_errno($ad_conn) . ' : ' . ldap_error($ad_conn) . "\n";
var_dump($ad_conn);

Output:
PHP Warning: ldap_errno(): supplied argument is not a valid ldap link resource in ad_test.php on line 5
PHP Warning: ldap_error(): supplied argument is not a valid ldap link resource in ad_test.php on line 5
:
bool(false)

I've tried connecting using ldap://server_name and ldap://ip_address. I've tried Active Directory and Sun ONE LDAP server. I've tried secured and unsecured. I've tried with and without port. I've tried 389, 636, ad 3268.

Anyone have suggestions?

Here is my environment:
Server OS:

SunOS host.domain.tld 5.10 Generic_142901-04 i86pc i386 i86pc
Update 8, x86 virtual machine

PHP version:

PHP 5.2.9 (cli) (built: May 6 2009 21:48:48)
Copyright (c) 1997-2009 The PHP Group
Zend Engine v2.2.0, Copyright (c) 1998-2009 Zend Technologies

PHP ldap extension:

LDAP Support => enabled
RCS Version => $Id: ldap.c,v 1.161.2.3.2.14 2008/12/31 11:17:39 sebastian Exp $
Total Links => 0/unlimited
API Version => 3001
Vendor Name => OpenLDAP
Vendor Version => 20339
SASL Support => Enabled