bitrix autoincrement custom field

AddEventHandler("iblock", "OnIBlockPropertyBuildList", array("CIBlockPropertyCustom", "GetUserTypeDescription"));

class CIBlockPropertyCustom
{
    public function GetUserTypeDescription()
    {
        return array(
            "PROPERTY_TYPE" => "N",
            "USER_TYPE" => "HTML",
            "DESCRIPTION" => "Autoincrement field",
            "GetPropertyFieldHtml" => array("CIBlockPropertyCustom", "GetPropertyFieldHtml"),
        );
    }

    // вывод поля свойства на странице редактирования
    public function GetPropertyFieldHtml($arProperty, $value, $strHTMLControlName)
    {
        return '<input type="hidden" name="' . $strHTMLControlName["VALUE"] . '" value="' . $value['VALUE'] . '">' . ($value['VALUE'] ?: 'обновится после добавления заказа');
    }
}

AddEventHandler("iblock", "OnBeforeIBlockElementAdd", Array("OrderAdd", "OnBeforeIBlockElementAddHandler"));

class OrderAdd
{
    // создаем обработчик события "OnAfterIBlockElementAdd"
    function OnBeforeIBlockElementAddHandler(&$arFields)
    {
        if ((int)$arFields['IBLOCK_ID'] == 33 and !$arFields['ID']) {
            CUserCounter::Increment(1, 'order_id');
            $arFields['PROPERTY_VALUES'][114] = CUserCounter::GetValue(1, 'order_id');
        }
        return;
    }
}