I have the following data ; POLine, BuyQty, EstimatedReceivingDate, PackSlip, ReceivedQty PO123-1, 6, 2018-05-01, Packslip123, 3 PO123-1, 6, 2018-05-01, Packslip456, 1 PO666-2, 4, 2018-05-02, Packslip777, 1 I group by POLine and added a variable called RemainingQty (BuyQty - TotalReceivedQty) so here I have POLine, BuyQty, EstimatedReceivingDate, RemainingQty PO123-1, 6, 2018-05-01, 2 PO666-2, 4, 2018-05-02, 3 All work well except I want to make a cumulative string that would include the 2 previous lines here so; PO123-1, 6, 2018-05-01, 2 PO666-2, 4, 2018-05-02, 3 Because I would use that variable in a tooltip so the user see some kind of drilldown when he over the report. It's not working correctly. I tried to create a variable. Name : Tooltip Calculation : non calculation function initial value expression : "" increment type : none reset type : none expression : ${Tooltip} + "n" + $V{RemainingQty} + " for POLine : " + $F{POLine} + " estimated date : " + $F{EstimatedReceivingDate} The problem seems related to the variable $V{RemainingQty} which is not evaluated at the correct time.