[SOLVED] Trouble with class cart

[neoshadybeat]

Hi

I'm doing a module for prestashop where i want to add elements to the cart, viewing the code i try this

<?php

require_once(dirname(__FILE__).'/config/config.inc.php');
require_once(dirname(__FILE__).'/init.php');

require_once(dirname(__FILE__).'/header.php');
   echo"hola mundo";

   $cart->updateQty(1,10);//id 10
require_once(dirname(__FILE__).'/footer.php');
?>

and it work's well, the problem is when i want to assign a attribute to it, when i try this

    $cart->updateQty(1,10,13);//id 10, attribute 13

it doesn't work, what is the problem?

thanks a lot ;-)
the problema was that the id attributte, is different to the attributte id assign to the product