BroadcastReceiver not receiving an alarm's broadcast

I have a code that sets a new repeating alarm (on production I'll use a inexactRepeating), but the BroadCastReceiver I've registered for handling it is not being called.

Here is the code where I set the alarm:

newAlarmPeriod = 5000; // For debugging

Intent alarmIntent = new Intent(this, GroupsCheckAlarmReceiver.class);
PendingIntent sender = PendingIntent.getBroadcast(this, Constants.CHECK_ALARM_CODE,
                                                  alarmIntent, 0);

AlarmManager am = (AlarmManager) getSystemService(ALARM_SERVICE);
am.setRepeating(AlarmManager.RTC_WAKEUP, System.currentTimeMillis() 
                + newAlarmPeriod, newAlarmPeriod, sender);

It seems to work and it triggers and alarm every five seconds, as seen in the output of "adb shell dumpsys alarm":

DUMP OF SERVICE alarm:
Current Alarm Manager state:

  Realtime wakeup (now=1269941046923):
  RTC_WAKEUP #1: Alarm{43cbac58 type 0 android}
    type=0 when=1269997200000 repeatInterval=0 count=0
    operation=PendingIntent{43bb1738: PendingIntentRecord{43bb1248 android broadcastIntent}}
  RTC_WAKEUP #0: Alarm{43ce30e0 type 0 com.almarsoft.GroundhogReader}
    type=0 when=1269941049555 repeatInterval=5000 count=1
    operation=PendingIntent{43d990c8: PendingIntentRecord{43d49108 com.almarsoft.GroundhogReader broadcastIntent}}
  RTC #1: Alarm{43bfc250 type 1 android}
    type=1 when=1269993600000 repeatInterval=0 count=0
    operation=PendingIntent{43c5a618: PendingIntentRecord{43c4f048 android broadcastIntent}}
  RTC #0: Alarm{43d67dd8 type 1 android}
    type=1 when=1269941100000 repeatInterval=0 count=0
    operation=PendingIntent{43c4e0f0: PendingIntentRecord{43c4f6c8 android broadcastIntent}}

  Broadcast ref count: 0

  Alarm Stats:
  android
    24390ms running, 0 wakeups
    80 alarms: act=android.intent.action.TIME_TICK flg=0x40000004
  com.almarsoft.GroundhogReader
    26ms running, 2 wakeups
    2 alarms: flg=0x4 cmp=com.almarsoft.GroundhogReader/.GroupsCheckAlarmReceiver

But for some reason my BroadCastReceiver is not being called when the alarm is triggered. I've declared it on the Manifest:

<receiver android:name=".GroupsCheckAlarmReceiver" />

And this is the abbreviated code:

public class GroupsCheckAlarmReceiver extends BroadcastReceiver{
  @Override
  public void onReceive(Context context, Intent intent) {
     Toast.makeText(context, "XXX Alarm worked.", Toast.LENGTH_LONG).show();
     Log.d("XXX", "GroupsCheckAlarmReceiver.onReceive");
  }

I found the problem, and it was a pretty stupid error. The <receiver> tag was inside the <manifest> but outside the <application> tags. Thanks for your time, guys.

Have you tried explicitly setting the 'enabled' attribute on the manifest receiver flag to true? I can't find any thing in the documentation that states what the default value is if it is not specified.