How can I add the total Qty amount for all products on Invoice?

I successfully added the total amount of products purchased to my new order email, I need this on the invoice print as well. This is the code I used for the woocommerce new order email….

Total Qty of Items Purchased

<?php $qty = 0;
foreach ( $order->get_items() as $item )
$qty += $item[‘qty’];
echo $qty; ?>

But I cant use it on the woocommerce_delivery_notes php it gives me an error. Any ideas?

Just to be clear…

Product > Quantity > $$Total
product1 10 $10
product2 5 $ 5

qty total 15 <——this is what I need!
sub-total $15
total $15

Thank you kindly!
Mimi

http://wordpress.org/extend/plugins/woocommerce-delivery-notes/