Guzzle and react Promise cause infine loop

Question

I use Guzzle 6 to call asynchrous request and I then use React Promise/Deferred and Event loop , then I use php-react-block to get result by resolved.

Firstly I send http Request as following:

public function callService($endpoint){
    $requestDeferred = new React\Promise\Deferred();
    $requestParams = new Request("POST", $endpoint, $header, $message);
    $client = new Client();//Guzzle  http client
    $client->sendAsync($requestParams)->then(
        function (ResponseInterface $res) use($requestDeferred) {
            // $res->getStatusCode() . "\n";
            $requestDeferred->resolve($res->getBody()->getContents());
        }, 
        function (RequestException $e) use($requestDeferred) {
            $requestDeferred->reject();
        }
    );
    return $requestDeferred->promise();
}

After I call this method as following

$loop = React\EventLoop\Factory::create();
$requestPromise = $this->callService( $endpoint);
$responseXml = Clue\React\Block\await($requestPromise, $loop);// I want to block/wait to until promise is resolved and get resolved value.

But when I call Clue\React\Block\await($requestPromise, $loop) , the system loops infinetly and any promise can not be resolved. Also I added queue->run() method to run method of related event (LibEvent). But system still loops infinetly.

Why the system loops infinetly?

Thanks for your helps