Symfony2 - ExceptionController - NotFoundHttpException - symfony

Question

I am trying to create a custom exception error page and I have been following Mike's tutorial. I have inserted the following code into config.yml, and created an ExceptionController in StoreBundle\Controller\ExceptionController.php. When I try to test my 404 error page by going local.store.com/fake-page, I get a NotFoundHttpException: No route found for "GET /fake-page" error. I thought my ExceptionController is suppose to redirect all users if a page is not found so I added a var_dump('testing') in it but it never dumped. I tried to remove the code I injected into config.yml and I get the default Symfony error page instead. Am I doing something wrong in config.yml?
Inserted into app/config/config.yml:
twig:
exception_controller: StoreBundle\Controller\ExceptionController::showAction
EDIT
I now think my problem is in my controller. This is what I have in StoreBundle\ControlleExceptionController.php. My error pages are in StoreBundle\Resources\views\Pages\Errors\404.html.twig and StoreBundle\Resources\views\Pages\Errors\500.html.twig
<?php
namespace StoreBundle\Controller;
use Symfony\Component\HttpKernel\Exception\FlattenException;
use Symfony\Component\HttpKernel\Log\DebugLoggerInterface;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Bundle\TwigBundle\Controller\ExceptionController as BaseExceptionController;
class ExceptionController extends BaseExceptionController
{
public function showAction(FlattenException $exception, DebugLoggerInterface $logger = null, $format = 'html')
{
$template = $this->container->get('kernel')->isDebug() ? 'exception' : 'error';
$code = $exception->getStatusCode();
return $this->container->get('templating')->renderResponse(
'StoreBundle:Exception:Pages/Errors:' . $code . '.html.twig', array(
'status_code' => $code,
'status_text' => Response::$statusTexts[$code],
'exception' => $exception,
'logger' => null,
'currentContent' => '',
));
}
}
}