I have tracked down my problem I was previously having being caused by multiple JOINs, could someone please give a direction to look in.
strSQL = "SELECT PROOLN_M.ITM_NUM, PROOLN_M.DSC_001, PROOLN_M.DSC_003, Sum(IIf(PROOLN_M.ORD_NUM<'90000000',PROOLN_M.QTY_SHP,0)) AS UNITS_PUR " & _
"...