protected function getValidVoucher($sShopVoucherCode)
    {
        $oValidVoucher = null;
        /** @var $oVoucher TdbShopVoucher */
        $oVoucher = TdbShopVoucher::GetNewInstance();

        if (strlen($sShopVoucherCode) >= 3) {
            if ($oVoucher->LoadFromFields(array('code' => $sShopVoucherCode, 'is_used_up' => '0'))) {
                $oValidVoucher = $oVoucher;
            }
        }

        return $oValidVoucher;
    }