4gl: Week Ending Queyr

Help! I need to produce a report that groups data by "week-ending". the "week" ends on Sunday. How the @#$% do I group records for this. I've tried to every unique 'invoice_date' where WeekDay(invoice_date) = 0 into an array, then do a foreach grouping all data where the invoice_date is between invoice_date - 6 and invoice_date, but I either get garbage or an error stating that a subquery has retrieved not exactly one row. (There is no subquery, it is a straigt select).... DECLARE date_cur CURSOR FOR SELECT UNIQUE invoice_date FROM invoices WHERE shift_code = cShift {Entered by user} AND WeekDay(invoice_date) = 0 FOREACH date_cur INTO qDate LET stDate = qDate - 6 LET eDate = qDate SELECT product, sum(invoice_amt), count(*) INTO r_Inv.product, r_Inv.invoice_amt, r_Inv.num WHERE shift_code = cShift AND invoice_date BETWEEN stDate and eDate GROUP BY product ORDER BY product {The query above generates the "Not Exactly one row" error } DISPLAY BY NAME r_Inv.* Any Ideas on what I'm doing wrong .... Thanks John Cokos