AJAX добавление в корзину - [VM1] Общие вопросы и ошибки

<?php
if( !defined( '_VALID_MOS' ) && !defined( '_JEXEC' ) ) die( 'Direct Access to '.basename(__FILE__).' is not allowed.' );

// Load the VirtueMart main parse code

global $mosConfig_offset,$Itemid;
if (file_exists( 'components/com_virtuemart/virtuemart_parser.php' )) {
    require_once('components/com_virtuemart/virtuemart_parser.php' );
} else {
    
}
require_once('administrator/components/com_virtuemart/virtuemart.cfg.php');
require_once('administrator/components/com_virtuemart/classes/vmAbstractObject.class.php');
require_once('administrator/components/com_virtuemart/classes/ps_checkout.php');
require_once('administrator/components/com_virtuemart/classes/ps_product.php');
$auth = $_SESSION['auth'];
$cart = $_SESSION['cart'];
$num_products = 0;
$order_subtotal = 0;
$ps_product= new ps_product;
for($i = 0; $i < $cart["idx"]; $i++)
{	
	$num_products += $cart[$i]["quantity"];
}
$var = array();
$order_subtotal = ps_checkout::calc_order_subtotal($var);
?>
<div id="shcart">
<div class='shoppingCartList'>
	В корзине товаров 
	<a href='index.php?option=com_virtuemart&amp;page=shop.cart'><b><?php echo $num_products ?> </b></a>, на 
	<a class="cartb" href='index.php?option=com_virtuemart&amp;page=shop.cart'><b><?php echo round($var['order_subtotal_withtax'],2); ?> </b> руб</a>
</div>
</div>