Flash messages not displaying in volt

I'm using Phalcon 2.0.6 (win7) with multiple inheritance templates

How can I display the flash messages?

This doesn't work

// service
use Phalcon\Flash\Direct as Flash;
use Phalcon\Flash\Session as FlashSession;

$di->setShared("session", function () {
    $session = new SessionAdapter();
    $session->start();

    return $session;
});

$di->set("flash", function () {
    $flash = new Flash();
    $flash->setImplicitFlush(false);

    return $flash;
});

$di->set("flashSession", function () {
    $flashSession = new FlashSession();
    $flashSession->setImplicitFlush(false);

    return $flashSession;
});

// controller
$this->flashSession->error('Flash Error!!!');
$this->flash->error('Direct Error!!!');

//$this->flashSession()->getMessages(); //works, return an array with messages

    <h1>Main layout</h1>

    {# {{ flashSession.getMessages() }} return null #}

    {{ flash.output() }}
    {{ flashSession.output() }}

    {% block content %}

    {% endblock %}

I have looked a lot of topics and issues but I did not found the solution.