在用户输入正确信息后重定向

Question

my PHP:

I'm trying to get the script to redirect after a user has entered the correct information. I know it has do with:

header("Location: site");

however it's not redirecting after submission. It does login though, because when I refresh, it redirects to the /site

and ideas?

$submit = $_POST['submit'];
                                $username = mysql_real_escape_string($_POST['username']);
                                $password = mysql_real_escape_string($_POST['password']);

                                if ($submit) {
                                    if ($username&&$password) {                                     
                                        $query = mysql_query("SELECT * FROM users WHERE username='$username'");
                                        $numrows = mysql_num_rows($query);                                      
                                            if ($numrows!=0) {                              
                                                while ($row = mysql_fetch_assoc($query)) {                                  
                                                    $dbusername = $row['username'];
                                                    $dbpassword = $row['password'];
                                                    $rank = $row['rank'];                                               
                                                }

                                                if ($username==$dbusername&&md5($password)==$dbpassword) {
                                                    header("Location: site");
                                                    $_SESSION['username']=$username;

                                                } else
                                                    echo "<div class='alert alert-error'><strong>Error:</strong> Incorrect password!</div>";                                            
                                            }else
                                                echo "<div class='alert alert-error'><strong>Error:</strong> The user you entered doesn't exist!</div>";                                    
                                    }else 
                                                echo "<div class='alert alert-error'><strong>Error:</strong> Please enter a username or password!</div>";                                   
                                }

here's my full code:

Full Short Code