The default AC7 invoice doesn't show credits, discounts, extra charges etc. It has the programming to do so, but the code doesn't work like it should. If you've ever added an extra line item for a Discount and then printed the invoice, you'll see what I mean.
Here's how to fix it so the line shows every time. As I said, this is a quick fix (I was in a hurry today) so the "Other:" charge line will show on every invoice whether it has a zero amount or not. Perhaps when I have more time I can make it fully functional as Able intended.
Edit the ~/Admin/Orders/Print/Invoices.aspx page and find this line:
And remove the entire visible= parameter so the line looks like this:
Now go display an invoice for an order. You should see a line for "Other:" and it will contain the proper dollars for any discounts, coupons, additional charges etc that are part of the order line items.