Hello.  I am designing a report that includes Costumers and Invoice Values.  I group this report by Costumers, and with the sum function I am able to list Costumers in one column and total invoiced during the year for each costumer.  I am able to sort this report by Costumers (ascending or descending), but when I try to sort by =Sum([InvoiceValue]) the sort option is not available. My intention is to sort my report by the sum of the invoices for each costumer.  Please help or let me know if I should address my question in a better way.  Thanks.