Erroneous Grand Total of calculated fields in pivot table

[JP]

I'm accessing an external DB to retrieve Quantities and Unit Weights, e.g.
Customer A bought 3 items of product X, with unit weight 10, and Customer B
bought 5 items of product Y, unit weight 12. In a pivot table, I'd like to
get the total weight, so I created a calculated field, Total Weight, as
Quantity*Unit Weight.

That works fine for individual customers A and B: I get respectively 30
(3*10), and 60 (5*12). But the Grand Total of the table is wrong: instead of
90 (30 + 60), I get 176! What happens is that, to calculate the Grand Total,
the table adds all the Quantities (3+5=8), adds all Unit Weights (10+12=22),
then multiplies them (8*22=176)!

How can I use calculated fields, still get correct Grand Totals?

I'm using Excel 2003.

 

[Debra Dalgleish]

You should ask the database administrator to create a query that
calculates the total weight, then use that field in your pivot table.

In addition to problems with the grand total, you could get incorrect
results if Customer A has multiple orders for product X. In that case,
the Unit weight would be included per order, and multiplied by the
number of items. So, for 3 orders of 3 items each, the total weight
would calculate as 9*30, instead of 9*10.

 

[JP]

Thank you, Debra. I conclude there's no way to do this within a PT itself.
Thanks for your quick reply, it saves me from wasting time looking for
something that doesn't exist...