Developers API Tutorial - A Real World Example

[LissaE]

I am trying to get this working and I am going wrong somewhere LOL I wonder if someone with more knowledge than me can tell me where I am going wrong?

http://www.zen-cart.com/wiki/index.p..._World_Example

I have copied the following code into includes/auto_loaders in a file called config.freeProduct.php

<?php

$autoLoadConfig[90][] = array('autoType'=>'class',
                              'loadFile'=>'observers/class.freeProduct.php');
$autoLoadConfig[90][] = array('autoType'=>'classInstantiate',
                              'className'=>'freeProduct',
                              'objectName'=>'freeProduct');

?>

And then the code underneath in the tutorial (changing the product id to my free product id) into includes/classes/observers/class.freeProduct.php

<?php
/**
 * Observer class used to add a free product to the cart if the user spends more than $x
 *
 */
class freeProduct extends base {
  /**
   * The threshold amount the customer needs to spend.
   * 
   * Note this is defined in the shops base currency, and so works with multi currency shops
   *
   * @var decimal
   */
  var $freeAmount = 10;
  /**
   * The id of the free product.
   * 
   * Note. This must be a true free product. e.g. price = 0 Also make sure that if you don't want the customer
   * to be charged shipping on this, that you have it set correctly.
   *
   * @var integer
   */
  var $freeProductID = 422;
  /**
   * constructor method
   * 
   * Attaches our class to the $_SESSION['cart'] class and watches for 2 notifier events.
   */
  function freeProduct() {
    $_SESSION['cart']->attach($this, array('NOTIFIER_CART_ADD_CART_END', 'NOTIFIER_CART_REMOVE_END'));
  }
  /**
   * Update Method
   * 
   * Called by observed class when any of our notifiable events occur
   *
   * @param object $class
   * @param string $eventID
   */
  function update(&$class, $eventID) {
    if ($_SESSION['cart']->show_total() >= $this->freeAmount && !$_SESSION['cart']->in_cart($this->freeProductID) ) {
      $_SESSION['cart']->add_cart($this->freeProductID);
    }
    if ($_SESSION['cart']->show_total() < $this->freeAmount && $_SESSION['cart']->in_cart($this->freeProductID) ) {
      $_SESSION['cart']->remove($this->freeProductID);
    }
    if ($_SESSION['cart']->in_cart($this->freeProductID)) {
      $_SESSION['cart']->contents[$this->freeProductID]['qty'] = 1;
    }
  }
}
?>

Uploaded them to the relevant directories...but when I added a product to cart I got a blank page, so I know I am missing something OR there is a mistake somewhere and any help would be appreciated to get this working because I really wanna LOL

**edit...I took the files out and I am still getting blank page, so maybe it's not this at fault....more digging for me it seems LOL