Display custom fields (textarea) on invoices

-- HikaShop version -- : 2.7
-- Joomla version -- : 2.5

Hi,
I have added a custom field (textarea) for a customer to add Shipping notes during checkout. I want the data from this textarea to show up on the invoices. I have tried adding the code to the invoice template:

<?php echo "Shipping Notes: ".$this->order->shippingnotes; ?>

where 'shippingnotes' is the column name. When I add this to the invoice template it only shows the string 'Shipping Notes:' but does not show the info that the customer filled out.

Any ideas?

Hi Nicolas,
I am editing the invoice file under Display>Views. I am not using the PDF invoice plugin

Attached (screenshot.jpg) is an image of how my custom field is set up. And screenshot1.jpg is how it is showing up on the invoice

And how would I go about doing that?
I've tried: <?php echo "Shipping Notes: ".$this->shipping_address->shippingnotes; ?>
and : <?php echo "Shipping Notes: ".$this->address->shippingnotes; ?>

Am I missing something?

Actually I got it to display by adding {shippingnotes} to the address_template file, but what I really want to do is have it displayed at the bottom of the invoice under Shipping method, Payment method (see attachment)