How to mark Vendor open settlement transaction using x++ code in Ax 2012

public void settlementnew(InvoiceId   _invoice)

{

    custvendopentransmanager            manager;

    VendTransOpen                       vendTransOpen;

    VendTrans                           vendTrans;

    ExchangeRateHelper                  exchangeRateHelper;

    AmountCur                           totalSettlement;

    //To mark particular invoice based on Acc num

    select vendtransopen where vendTransOpen.AccountNum ==AccountNumb

                join vendTrans where vendTrans.Invoice == _invoice
                     && vendTrans.RecId == vendtransopen.RefRecId
                    && vendTrans.AccountNum == vendTransOpen.AccountNum;

   

    if(vendtransopen)

    {

        //To check transaction line which we want to settle

        manager = custvendopentransmanager::construct(ledgerJournalTrans);

        manager.updateTransMarked(vendTransOpen,true);

   

        //To get total settlement

        exchangeRateHelper = ExchangeRateHelper::newCurrency(Ledger::primaryLedger(CompanyInfo::findDataArea(ledgerJournalTrans.Company).RecId),ledgerJournalTrans.CurrencyCode);

        totalSettlement    = SpecTransManager::getTotalSettleAmountForSpecReference(

                                ledgerJournalTrans.Company,

                                ledgerJournalTrans.TableId,

                                ledgerJournalTrans.RecId,

                                ledgerJournalTrans.CurrencyCode,

                                ledgerJournalTrans.Company,

                                ledgerJournalTrans.TransDate,

                                exchangeRateHelper.prepareExchangeRateForStorage(ledgerJournalTrans.crossrate()));

        //To update in ledgerJournal trans

        ttsBegin;

        ledgerJournalTrans.selectForUpdate(true);

        ledgerJournalTrans.AmountCurDebit   = abs(totalSettlement);

        ledgerJournalTrans.SettleVoucher    = SettlementType::SelectedTransact;

        ledgerJournalTrans.update();

        ttsCommit;

    }

}

http://www.andesoft.net/automatic-mark-settlement-transactions-payment-journal-ax-2012/