Flash messages on Symfony 2.0 doesn't work correctly
===

I use Symfony 2.0.16 and I have a problem with flash messages. I didn't found on the web any issues about my problem.

I read doc about flash messages [HERE][1], I copy this sample code. And when I test it, it half works.

If I don't put *setFlash* in the controller, I see nothink (Normal). But if I put it into, only the *<div class="flash-notice"></div>* appear, *{{ app.session.flash('notice') }}* wasn't wrote !


The documentation code :

**Controller**

    public function updateAction()
    {
        $form = $this->createForm(...);

        $form->bindRequest($this->getRequest());
        if ($form->isValid()) {
            // do some sort of processing

            $this->get('session')->setFlash('notice', 'Your changes were saved!');

            return $this->redirect($this->generateUrl(...));
        }

        return $this->render(...);
    }

**Template**

    {% if app.session.hasFlash('notice') %}
        <div class="flash-notice">
            {{ app.session.flash('notice') }}
        </div>
    {% endif %}

  [1]: http://symfony.com/doc/current/book/controller.html#flash-messages