Nick
One expression I had a problem with had to do with HasData, a check to make sure that a subreport has data.
The following works in Access 2000...
=IIf([rptInvoiceDetails].[Report].[HasData]=-1,[rptInvoiceDetails]![txtBalance],0)
But that won't work in Access 2003, even though the file format is Access 2000. Access 2003 needs the additional .Report operator in the last half of the expression. i.e.
=IIf([rptInvoiceDetails].[Report].[HasData]=-1,[rptInvoiceDetails].[Report]![txtBalance],0)
It was a bit frustrating to get blank text boxes on an Invoice, until I figured out where the problem was. When I did the solution was fairly simple, because Access 2000 accepts the expression with or without .Report
Anyway, thanks for the feedback.
Tom