title: Symfony 2 registering a doctrine listener not working
body: <p>Services.xml file:</p>
  
  <pre><code>&lt;?xml version="1.0" ?&gt;
  
      &lt;container xmlns="http://symfony.com/schema/dic/services"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd"&gt;  
  
          &lt;services&gt;
              &lt;service id="task.task_history_insertion" class="Acme\Bundle\EventListener\TaskHistoryInsertion"&gt;
                  &lt;argument type="service" id="service_container" /&gt;
                  &lt;tag name="doctrine.event_listener" event="postPersist" method="postPersist"/&gt;
              &lt;/service&gt;
          &lt;/services&gt;
      &lt;/container&gt;
  </code></pre>
  
  <p>TaskHistoryInsertion.php</p>
  
  <pre><code>class TaskHistoryInsertion implements EventSubscriber
  {
  
      protected $container;
  public function __construct(ContainerInterface $container)
  {
      $this-&gt;container = $container; 
  }
  
  public function getSubscribedEvents()
  {
      return array(
          Event::postPersist
      );
  }
  
  public function postPersist(LifecycleEventArgs $args)
  {
           //not being called
          }
  }
  </code></pre>
  
  <p>Any ideas on why postPersist isn't being called after persisting?</p>