help with totaling portals

[spragueg]

Sorry for the double post.

I have two files. Invoices and Items.

In the Items file I have a the following calculations...

subtotal = price * qty

extras_subtotal = extra * qty

final subtotal = subtotal + extras_subtotal

In the Invoices file I have the following calculations...

net = Sum(items::final subtotal)

sales tax = net* .5

final total = net + sales tax +shipping

The calculations in the invoice file don't show up until I click in the field and then exit the field.

Questions:

Am I doing something wrong?

If so, what would you suggest as an altenate method?

Thanks,

Graham Sprague

[This message has been edited by spragueg (edited August 24, 2000).]