Open application after clicking on Notification

I have a notification in my app with the following code:

//Notification Start

   notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

   int icon = R.drawable.n1; 
   CharSequence tickerText = "Call Blocker";
   long when = System.currentTimeMillis(); //now
   Notification notification = new Notification(icon, tickerText, when);
   Intent notificationIntent = new Intent(context, Main.class);
   PendingIntent contentIntent = PendingIntent.getActivity(context, 0, notificationIntent, 0);

   Context context = getApplicationContext();
   CharSequence title = "Call Blocker";
   text = "Calls will be blocked while driving";

   notification.setLatestEventInfo(context, title, text, contentIntent);

   notification.flags |= Notification.FLAG_ONGOING_EVENT;
   notification.flags |= Notification.FLAG_SHOW_LIGHTS;
   notificationManager.notify(1, notification);

}

My notifications fires very well, but my problem is that, when I click on notification in Notification Center, it does not start my app.

Basically, after clicking on my notification nothing happens! What should I do, in order to start my Main activity after clicking on my notification. Thanks.