I have a continuos form that shows the unitary prize of an item, the quantity and in a control I show the subtotal: UnitaryPrize*Quantity.
I would like to show the total of all subtotals. That means to put this expression in a control placed in the header/footer of the form:
Obviously it doesn't work.
The reason is probably the expression that generates the subtotal:
This because the unitary prize is shown in a combo box based on a query with two collumns: id and unitaryprize. Id collumn is hidden (width=0). So I have to take the value in the right column: unitaryprize and not id.

Do you know how to solve this?