Thanks Marshall!  I see how that works now.  I'm trying to take this one step
further so I have another question.

I'm trying to sum fields on the report from 2 different levels:  One from the
detail section + 2 other fields from the group header/footer.  The
combination of the 2 is causing me some frustration.

Incidentally, the expression in txtBidTotal is:
=Sum([LineTotalSellPrice])+[SalesTaxAmount]+[UseTaxAmount]
LineTotalSellPrice exists in the detail section so there are multiple records.

SalesTaxAmount & UseTaxAmount exist only once per group.

I achieved an accurate total of the LineTotalSellPrice where BidType = "Base
Bid" with:
=Sum(IIf([BidType]="Base Bid",[LineTotalSellPrice],0))

The problem I come up with is that I can't get it to add just one
SalesTaxAmount & UseTaxAmount per group.  It adds one per each record in the
detail section.  I can get the IIf statement to work properly in the group
header/footer, but that leaves me with not being able to sum those fields.
It would be really nice if aggregate fuctions recognized controls!  My
thought was to create 3 text boxes in the report footer:  1 to total
LineTotalSellPrice, 1 to total SalesTaxAmount, and 1 to total UseTaxAmount,
and then I could total those 3 controls.  

I have tried numerous different configurations of expressions, but it comes
down to getting it to add just one SalesTaxAmount & UseTaxAmount per group
where BidType = "Base Bid".  If you can offer any further suggestions, I
would greatly appreciate it!
Thanks again!
Slez