I currently have an order item table that includes a quantity , price and a subtotal field. How do I get this calculations. I tried it two different way. first I tried building an expression in the subtotal field
=[OrderItems]![Product_Quantity]*[OrderItems]![product_Price]
This did not work. So I tried changing the Sub_total field in the OrderItems table to calculation then added the expression above, but got the following error
here is the form, How do i generate sub total, and then a total field at the bottom of form