title: Symfony controller embedd error: The controller for URI "/_fragment" is not callable
body: <p>I'm calling a render like so in my Twig template (line 18)</p>
  
  <pre><code>{{ render(controller('AcmeReadingBundle:Default:newAction')) }}
  </code></pre>
  
  <p>And the controller is</p>
  
  <pre><code>public function newAction(Request $request)
      { 
        $message = new Message();
        $form = $this-&gt;createFormBuilder($message)
          -&gt;add('body', 'text')
          -&gt;add('save', 'submit')
          -&gt;getForm();
  
        $form-&gt;handleRequest($request);
  
        return $this-&gt;render('AcmeReadingBundle:Default:new.html.twig', array(
            'form' =&gt; $form-&gt;createView(),
          ));
      }
  </code></pre>
  
  <p>And the new.html.twig file is </p>
  
  <pre><code>{{ form(form) }}
  </code></pre>
  
  <p>I keep getting this error: </p>
  
  <pre><code>An exception has been thrown during the rendering of a template ("The controller for URI "/_fragment" is not callable.") in AcmeReadingBundle:Default:show.html.twig at line 18.
  </code></pre>