protected function UpdateListData()
    {
        $this->dNumberOfItems = 0;
        $this->dProductPrice = 0;

        $this->dTotalWeight = 0;
        $this->dTotalVolume = 0;
        $tmpPointer = $this->getItemPointer();
        $this->GoToStart();
        while ($oItem = &$this->Next()) {
            if ($oItem->dAmount <= 0) {
                $this->RemoveArticle($oItem);
            } else {
                $this->dNumberOfItems += $oItem->dAmount;
                $this->dProductPrice += $oItem->dPriceTotal;

                $this->dTotalWeight += $oItem->dTotalWeight;
                $this->dTotalVolume += $oItem->dTotalVolume;
            }
        }
        $this->setItemPointer($tmpPointer);
    }