As CommonsWare suggested, I ran the app on a 2.3 emulator and it crashed. Reason being ContentIntent was not set. GingerBread expects a ContentIntent. So I added a dummy pending intent like :
PendingIntent pi = PendingIntent.getBroadcast(this, 0, new Intent(), PendingIntent.FLAG_UPDATE_CURRENT);
Notification notification = new NotificationCompat.Builder(this).setAutoCancel(true)
.setContentTitle(userString)
.setContentText("Queued")
.setContentIntent(pi)
.setSmallIcon(R.drawable.stat_sys_download_done)
.setWhen(System.currentTimeMillis())
.setTicker(tickerText)
.build();