Hvorfor virker det ikke? :O

PHP kode 

 <?php
 
     session_start();
     ob_start();
 
     $username = $_GET['username'];
     $password = md5($_GET['password']);
 
     require("../CMS/database.php");
     
     $query = "SELECT * FROM users WHERE username = '" . $username . "' AND password = '" . $password . "'";
     
     $result = mysql_query($query);
 
     echo "<br />" . mysql_num_rows($result);
 
     if(mysql_num_rows($result) > 0){
 
     echo "hej world";
 
         while($brugerData = mysql_fetch_assoc($result)){
             //echo "tuttelu world";
                 $_SESSION['username'] = $brugerData['username'];
                 $_SESSION['password'] = $brugerData['password'];
                 $_SESSION['email'] = $brugerData['email'];
                 $_SESSION['id'] = $brugerData['id'];
         
         }
         //print_r($brugerData);
         header("location: ../CMS/index.php");
         
     } else {
     //echo "farvel world";
     unset($_SESSION);
     header("location: ../index.php?wrong=password");
     }
 ?>