mostSpecificSubdivision->isoCode is empty

Hi support,

I try to get the iso code for the region of an IP. mostSpecificSubdivision->name returns the good value, but when I try to get the isoCode, the value is always empty. Is it a bug? What am I doing wrong? ` $geoip = Geoip2::getInstance(); $geoip->getRegionCode('222.213.14.33'); class Geoip2 {

private static $instance = null;

private $geoip;

protected static $records = array();

private function __construct() {
    $this->geoip = new Reader('/usr/local/src/DBIP-City.mmdb');
}

/**
 * @return Geoip2
 */
public static function getInstance() {
    if (is_null(self::$instance)) {
        self::$instance = new self();
    }
    return self::$instance;
}

/**
 * @param $ip
 *
 * @return \GeoIp2\Model\City|mixed
 * @throws \GeoIp2\Exception\AddressNotFoundException
 * @throws \MaxMind\Db\Reader\InvalidDatabaseException
 */
private function getRecord($ip) {
    if (!array_key_exists($ip, self::$records)) {
        self::$records[$ip] =  $this->geoip->city($ip);
    }
    return self::$records[$ip];
}

public function getCountryCode($ip) {
    try {
        $record = $this->getRecord($ip);
        return strtolower($record->country->isoCode);
    } catch (\Exception $e) {
        return 'us';
    }
}

public function getRegionCode($ip) {
    try {
        $record = $this->getRecord($ip);
        return $record->mostSpecificSubdivision->isoCode.'|'.$this->getCountryCode($ip);
    } catch (\Exception $e) {
        return '|us';
    }
}

} `

maxmind / GeoIP2-php

mostSpecificSubdivision->isoCode is empty #177