Paypal Express checkout ajax response problem

[Funtechireland]

Can anyone check there ajax.php file under paypal/expresscheckout.

As when I click the color of the product image is not switching and ajax response is die("1"); 

Here is the link:

http://www.funtechglobal.com/en/phone-case/478-iphone-66s-leather-wallet-case.html

 

 and the code 

 

if ($quantity && $quantity > 0) {

    /* Ajax response */

    $id_product = (int) Tools::getValue('id_product');

    $id_product_attribute = (int) Tools::getValue('id_product_attribute');

    $product_quantity = Product::getQuantity($id_product, $id_product_attribute);

    $product = new Product($id_product);

 

        //var_dump($id_product);

        //die;

 

 

    if (!$product->available_for_order) {

        die('0');

    }

 

    if ($product_quantity > 0) {

 

      // die;

        die('1');

    }

 

    if ($product_quantity <= 0 && $product->isAvailableWhenOutOfStock((int) $product->out_of_stock)) {

       //    var_dump $product_quantity;

        die('2');

    }

 

}

die('0');