Delete facebook session cookie from my application on users logout

Question

I am working in an application which is using facebook connect to log in the users using their facebook account.

Everything works fine except in the following case:<

Answer 1

 APPID, 'secret' => SECRET, 'fileUpload' => true ) );

// if we are being visited by someone trying to logout, lets me sure they get logged out!
if( isset( $_GET['logged_out'] ) ) {
    setcookie( "PHPSESSID", "", (time()-3600) );
    header( "location: " . URL );
    exit();
}

// lets try to get the users id
$user_id = $facebook->getUser();
// try to get their access token
$access_token = $facebook->getAccessToken();

// if we have an id
if($user_id) {

    // from the offset, we're good to go...
    $logged_in = true;

    echo "
Logged in
";
    $params = array( 'next' => URL . '?logged_out' );
    $return .= '
logout';

}else{

    // login man!
    $login_url = $facebook->getLoginUrl( 
        array( 
            'scope' => 'read_stream, publish_stream, manage_pages, photo_upload',
            'next' => URL . '?logged_in' 
        ) 
    );
    $return .= 'Please login.';

}

echo $return

?>