I read through the WIKI and I thought I got the general idea... but all I get is a blank page! I'm trying to get a message header when someone adds an item(s) to their cart.

this is what I have in /includes/classes/observers/class.addProductMessage.php
Code:
<?php
/**
 * Observer class used to add a free product to the cart if the user spends more than $x
 *
 */
class addProductMessage extends base {

  function addProductMessage() {
    $_SESSION['cart']->attach($this, array('NOTIFIER_CART_ADD_CART_END');
  }

  function update(&$class, $eventID) {
  $messageStack->add_session('header', 'test!', 'success');
  }
}
?>
And this is what I have in /includes/auto_loaders/config.addProductMessage.php
Code:
<?php
$autoLoadConfig[85][] = array('autoType'=>'class',
                              'loadFile'=>'observers/class.addProductMessage.php');
$autoLoadConfig[85][] = array('autoType'=>'classInstantiate',
                              'className'=>'addProductMessage',
                              'objectName'=>'addProductMessage');
?>
From the examples given, I presumed this would work on the first shot because its so simple! What am I doing wrong???

- Steven