My poor calculation is mushy, could you please help me out?

[animazing]

So I have been trying to clean up a mess on Filemaker that someone set us up wrong...

The invoice is for a gallery.

For our invoice, we have to have a Retail Price and a Sale Price (since we discount a lot) for every piece of art... Firstly, I would like the "retail price" to go into the "sale price" even if it is not on sale..because the below desired calculation needs to be a sum of the sale price.

On the bottom of the invoice I have lined down..

"Total Sale Price" (pull from each item on invoice)

"Tax"

"Shipping Cost" (only once)

Other (In this field I would like to show any Shipping Discounts, so maybe negative sometimes)

"Total Invoice Cost"

We need these to total up to give the correct amount for the invoice..

I need to know what field need to be "global" and I thought I could make this into a simple calculation but it is not working. What I have right now is..

Invoice Subtotal + Sales_Tax_Total + Shipping - Shipping Discount

Please help me.. I am really new to filmaker!

[bcooney]

See if this demo helps.

InvoiceDemo.zip