Unable to fetch forum config.

I have to do all step required to install punBB, at the end of install process, I did create config.php base on script:
<?php

$db_type = 'mysql';
$db_host = 'localhost';
$db_name = 'punbb';
$db_username = 'root';
$db_password = '';
$db_prefix = 'cpt';
$p_connect = false;

$cookie_name = 'punbb_cookie';
$cookie_domain = '';
$cookie_path = '/';
$cookie_secure = 0;

$language = 'en';

define('PUN', 1);

?>

BUT when I try to load index.php. my browser returned: Unable to fetch forum config.
How can I solve this problem??
Thanks for your help and sorry about my English!
Best regard!
NAPVD

PS: My PC is runing Win2k ADV Server and IIS 6