无法使用ReactPHP连接到Meetup API

I want to connect to Meetup RSVP API, using ReactPHP, but fail. This is how I do it:

require __DIR__ . '/vendor/autoload.php';

$loop = React\EventLoop\Factory::create();
$connector = new React\Socket\Connector($loop);

$connector->connect('ws://stream.meetup.com/2/rsvps')->then(function (React\Socket\ConnectionInterface $connection) {
    echo 'Connected!';
});

I do not get any error messages, but I do not see Connected! message. I also tried Pawl library this way:

$loop = React\EventLoop\Factory::create();
$connector = new Ratchet\Client\Connector($loop);
$connector('ws://stream.meetup.com/2/rsvps')
->then(function (Ratchet\Client\WebSocket $conn) use ($http) {

    $conn->on('message', function($msg) use ($conn) {
        echo "Received: {$msg}
";
        $conn->close();
    });


}, function (\Exception $e) use ($loop) {
    echo "Could not connect: {$e->getMessage()}
";
    $loop->stop();
});

But to no avail. I see no message from on message handler, and I see no message from exception handler. So, what is wrong with that and how can I fix it?