Sage 100

The total is displaying as zero in Invoice Data entry I've written the script for the extension amount as follows. Can you pls clarify which column should be used to store the total?

I have the following scenario: I invoiced the client last month and posted. The customer called this month saying that the price is incorrect and he was overcharged. I know I can do a credit memo in AR invoicing and credit as “Charge”. But us there…