updateQnty = "UPDATE tblSupplySources INNER JOIN ((tblWarehouseLocations " & _
            "INNER JOIN tblSupplySource_WarehouseLocation ON tblWarehouseLocations.WLocation_ID = tblSupplySource_WarehouseLocation.SWLocation_ID)) " & _
            "ON tblSupplySources.SupplySourceID = tblSupplySource_WarehouseLocation.Supply_Source_ID " & _
            "SET tblWarehouseLocations.WQuantity = '" & Me.txtQntyRecd & "'" & _
              "WHERE (((tblSupplySource_WarehouseLocation.Supply_Source_ID)= " & Me.cboSupplySource & ") " & _
             " AND ((tblWarehouseLocations.WLocation_ID)=" & lookupValue & "))"
     CurrentDb.Execute updateQnty, dbFailOnError

SET tblWarehouseLocations.WQuantity = tblWarehouseLocations.WQuantity + '" & Me.txtQntyRecd & "'"