Deshalb habe ich mir ein solches Stück Code selbst erarbeiten dürfen. Dabei vergleiche ich ganz einfach den vorher reservierten Wert mit dem danach reservierten Wert. Ist dieser ident, gehe ich davon aus, daß die Reservierung nicht gut gegangen ist.

static void reserveSalesLine(Args _args)
{
    InventTransIdSumSingleStatus inventTransIdSumSingleStatus;
    SalesLine salesLine;
    InventMovement inventMovement;
    InventDim inventDim;
    InventDimParm inventDimParmCriteria;
    InventQtyReservPhysical oldReservedQty;
    InventQtyReservPhysical newReservedQty;
    InventUpd_Reservation inventUpd_Reservation;
    InventQty reserveQty;

    // Inline method to get current reserved quantity for specific inventDim
    InventQtyReservPhysical getReservedQty()
    {
        inventDimParmCriteria.initFromInventDim(inventDim);        

        inventTransIdSumSingleStatus = InventTransIdSumSingleStatus::newTransOriginIdStatus(InventTransOriginSalesLine::findInventTransOriginId(salesLine.DataAreaId, salesLine.InventTransId),
                                                                                            StatusReceipt::None,
                                                                                            StatusIssue::ReservPhysical);
        inventTransIdSumSingleStatus.parmInventDimCriteria(inventDim);
        inventTransIdSumSingleStatus.parmInventDimParmCriteria(inventDimParmCriteria);

        return inventTransIdSumSingleStatus.reservPhysical();
    }

    // Sales order line
    salesLine = SalesLine::findInventTransId('012431');
    inventMovement = InventTrans::findTransId(salesLine.InventTransId).inventMovement(true);

    // Build inventDim-Record, where the quantity should be reserved
    inventDim.clear();
    inventDim.InventSiteId      = "1";
    inventDim.InventLocationId  = "12";
    inventDim.wmsLocationId     = "12";
    inventDim = InventDim::findOrCreate(inventDim);

    // Get current physical reserved Quantity
    oldReservedQty = getReservedQty();

    // Set quanity which should be reserved (negative values to reserve, postive value to unreserve)
    reserveQty = -2;

    inventUpd_Reservation = InventUpd_Reservation::newInventDim(inventMovement,
                                                                inventDim,
                                                                reserveQty,
                                                                true);
    inventUpd_Reservation.updateNow();

    // Get new reserved quantity
    newReservedQty = getReservedQty();

    // Compare old and new reserved quantity to identify if reservation failed
    if(oldReservedQty == newReservedQty)
    {
        error("Reservation failed.");
    }
}