public function isWorking()
    {
        if (empty($_SERVER[self::TEST_SERVER_VAR])
            && empty($_SERVER[self::TEST_SERVER_VAR_ALT])
            && empty($_SERVER[self::TEST_SERVER_VAR_ALT_IPV6])
        ) {
            return Piwik::translate("UserCountry_CannotFindGeoIPServerVar", self::TEST_SERVER_VAR . ' $_SERVER');
        }

        return true; // can't check for another IP
    }