Have you tried (it still may not work because of sum of multiplied fields?):

SELECT invoice.nInvoiceNumber, invoice.dInvoiceDate,
SUM(invoicedetail.nQuantity*invoicedetail.nUnitPrice) AS nTotal
FROM Invoice, InvoiceDetail
WHERE Invoice.nID = InvoiceDetail.nParentID
GROUP BY nInvoiceNumber, dInvoiceDate Order BY nInvoiceNumber

>What is wrong???????? I know I can bypass the problem with the SET ENGINEBEHAVIOUR 70, but I would really like to know what the correct syntax should be.
>
>TIA