Everything else works except this.. it comes up with a header error -.- please help.


<?php
 // Connects to your Database
include ("database.php");

 //Checks if there is a login cookie
 if(isset($_COOKIE['ID_my_site']))

 //if there is, it logs you in and directes you to the members page
 {  $username = $_COOKIE['ID_my_site'];
    $pass = $_COOKIE['Key_my_site'];
        $check = mysql_query("SELECT * FROM users WHERE username = '$username'")or die(mysql_error());
    while($info = mysql_fetch_array( $check ))
        {
        if ($pass != $info['password'])
            {
                        }
        else
            {
            header("Location: members.php");

            }
        }
 }
 //if the login form is submitted
 if (isset($_POST['submit'])) { // if form has been submitted

 // makes sure they filled it in
    if(!$_POST['username'] | !$_POST['pass']) {
        die('You did not fill in a required field.');
    }
    // checks it against the database

    if (!get_magic_quotes_gpc()) {
        $_POST['email'] = addslashes($_POST['email']);
    }
    $check = mysql_query("SELECT * FROM users WHERE username = '".$_POST['username']."'")or die(mysql_error());

 //Gives error if user dosen't exist
 $check2 = mysql_num_rows($check);
 if ($check2 == 0) {
        die('That user does not exist in our database. <a href=add.php>Click Here to Register</a>');
                }
 while($info = mysql_fetch_array( $check ))
 {
 $_POST['pass'] = stripslashes($_POST['pass']);
    $info['password'] = stripslashes($info['password']);
    $_POST['pass'] = md5($_POST['pass']);

 //gives error if the password is wrong
    if ($_POST['pass'] != $info['password']) {
        die('Incorrect password, please try again.');
    }
     else
 {
 // if login is ok then we add a cookie
     $_POST['username'] = stripslashes($_POST['username']);
     $hour = time() + 3600;
 setcookie(ID_my_site, $_POST['username'], $hour);
 setcookie(Key_my_site, $_POST['pass'], $hour);

 //then redirect them to the members area
 header("Location: members.php");
 }
 }
 }
 else
 {

 // if they are not logged in
 ?>
 <form action="<?php echo $_SERVER['PHP_SELF']?>" method="post">
 <table border="0">
 <tr><td colspan=2><h1>Login</h1></td></tr>
 <tr><td>Username:</td><td>
 <input type="text" name="username" maxlength="40">
 </td></tr>
 <tr><td>Password:</td><td>
 <input type="password" name="pass" maxlength="50">
 </td></tr>
 <tr><td colspan="2" align="right">
 <input type="submit" name="submit" value="Login">
 </td></tr>
 </table>
 </form>
 <?php
 }

 ?>