Cannot Add The Vat From The Voucher To The Total Vat

Hi,



I have a problem with the invoice which is generated on the admin area under the Order => View orders => Click on an order => Click 'View'.



The problem is that when a voucher is purchased, its VAT isn't added to the total VAT. When there is no voucher, the total VAT is calculated correctly.



On this file:

design/backend/templates/views/orders/details.tpl

I made my changes and added the bolded text:

value=$tax_data.tax_subtotal + $gift.display_subtotal

but this variable is not defined here. It is defined on this file:

design/backend/templates/addons/gift_certificates/hooks/orders/extra_list.post.tpl



Is there a way I could use $gift.display_subtotal variable on this file:

design/backend/templates/views/orders/details.tpl



Thanks for your help!