php ldap_search Operations error - php

Question

I want to use the following php script to retrieve AD Users (Windows 2008R2) who have the "proxyAddresses" attribute set:
<?php
$ldaprdn = 'ldapbind#test.net';
$ldappass = 'testpass';
$ldapconn = ldap_connect("ldap://10.1.20.254:389")
or die("Could not connect to LDAP server.");
ldap_set_option($ldapconn, LDAP_OPT_PROTOCOL_VERSION, 3);
ldap_set_option($ldapconn, LDAP_OPT_REFERRALS, 0);
if ($ldapconn) {
$ldapbind = ldap_bind($ldapconn, $ldaprdn, $ldappass);
if ($ldapbind) {
echo "LDAP bind successful...\n";
$result = ldap_search($ldapconn, "CN=Users,DN=test,DN=net", "(proxyAddresses=*)")
or die ("Error in serach query: " . ldap_error($ldapconn));
$data = ldap_get_entries($ldapconn, $result);
print_r($data);
} else {
echo "LDAP bind failed...";
}
}
?>
It binds successful, but then i get warning and error message:
PHP Warning: ldap_search() Operations error in ..... on line .. (the ldap_search line)
and
Error in search query: Operations error
When i execute an ldapsearch on the console:
ldapsearch -h 10.1.20.254 -p 389 -D 'ldapbind#test.net' -w 'testpass' -b 'CN=Users,DC=test,DC=net' '(proxyAddresses=*)' cn proxyAddresses mail
i get the desired results.
It's running on "CentOS release 6.4 (Final).
Thanks in advance