Call to undefined function ldap

Hello,

I want to set up an intranet site where user log in with their Active Directory username and password using LDAP.

I have Appserv 2.5.7 running on my machine (windows xp SP2):
# Apache Web Server Version 2.2.3
# PHP Script Language Version 5.1.6
# MySQL Database Version 5.0.24a
# phpMyAdmin Database Manager Version 2.9.0.2

We have an exchange 2003 server with ldap.

I use the following script to let users log in:

Code: (php)

<?php

$ldap['host'] = '192.168.1.2';
$ldap['port'] = 389;

function ldap_authenticate($username, $password) {
  global $ldap;

  $conn = ldap_connect($ldap['host'],$ldap['port']);

if ($conn) {
        if (ldap_bind( $conn, $username, $password) ) {
            ldap_close($conn);
            return TRUE;
        }
  }
  ldap_close($conn);
  return FALSE;
}

if (!ldap_authenticate('user@domain.local', 'pass')) {
  echo 'Authorization Failed';
} else {
    echo 'Welcome';
}

?>

When i use this code, i get the following:

Quote

Call to undefined function ldap_connect()

Appserv has ldap-support and i have uncommentet "extension=php_ldap.dll" in the php.ini file but still no result.

Can anybody help me?