cookie e scrittura

[antoce]

Cari Amici,
ho questo scritto:

<?  ob_start();?>
<?
header("Pragma: ");
header("Cache-Control: ");
header("Expires: Mon, 26 Jul 1980 05:00:00 GMT");
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
header("Cache-Control: no-store, no-cache, must-revalidate, proxy-revalidate");
header("Cache-Control: post-check=0, pre-check=0", false);
//set global variables
global $username,$password;

//header("Pragma: no-cache");
// EDIT HERE TO SUIT YOUR NEEDS
//set usernames and passwords
//only letters and numbers (no spaces) Known as can contain spaces
$uname[1] = "prova";
$upass[1] = "caserta";
$known_as[1] = "prova";
//additional users can be added
$uname[2] = "prova1";
$upass[2] = "caserta";
$known_as[2] = "prova1";


//the login page
$login_page = "login.php";
//where to go after login
$success_page = "scelta.php";
//the path to validate.php
$validate_path = "full path to validate.php";
//login failed error message
$login_err = '<div align="center">Your User Name or Password was incorrect[/b]</div>';
//no fields filled in
$empty_err = '<div align="center">[b]You need to login with your User Name and Password[/b]</div>';
//something entered that wasn't a letter or number error message
$chr_err = '<div align="center">[b]Please retry[/b]</div>';

Ma quando mi loggo mi restituisce l'errore $empty_err
Secondo voi perchè?

[antoce]

questo è il ciclo che stampa l'errore

 if($username == "" && $password == ""  && !isset($_COOKIE["this_cookie"])){
                print($empty_err);
                include($login_page);
                exit();
        } 

[antoce]

up

[antoce]

non vi è mai capitata una cosa del genere?