Android notification not working

I've been attempting to get a notification of a successful upload from an ASyncTask to work all day. I'm not getting any errors from my current code but I can't get the notification to show in the notification bar (or anywhere else). I get no messages in LogCat and no notification appears in the Notification bar. This is my code:

Notification mNotification = new Notification(icon, tickerText, when);

CharSequence contentTitle = "upload completed.";
CharSequence contentText = "upload completed.";

Intent notificationIntent = new Intent(context, CastrActivity.class);
PendingIntent contentIntent = PendingIntent.getActivity(context, 0, notificationIntent, PendingIntent.FLAG_NO_CREATE);
mNotification.contentIntent = contentIntent;
mNotification.setLatestEventInfo(context, contentTitle, contentText, contentIntent);
mNotificationManager.notify(NOTIFICATION_ID, mNotification);

This is called from the onPostExecute() method of an ASyncTask. I'm a bit confused on the PendingIntent part, to be honest. Any clarification of what I suspect to be incorrect code there would be greatly appreciated.