Change the query SQL to this:
SELECT tbl_idq_all.scode, tbl_idq_all.Date, tbl_idq_all.po_qty, DSum("po_qty","tbl_idq_all","[Date] < #" & [Date] & "# And scode='" & [scode] & "'")+Nz([po_qty],0) AS RunningTotal
FROM tbl_idq_all
ORDER BY tbl_idq_all.scode, tbl_idq_all.Date;
And when I do that...