Android :: Set Alarm To Fire Properly At Fixed Time?

Calendar c = new GregorianCalendar();
c.add(Calendar.DAY_OF_YEAR, 1);
c.set(Calendar.HOUR_OF_DAY, 23);
c.set(Calendar.MINUTE, 22);
c.set(Calendar.SECOND, 0);
c.set(Calendar.MILLISECOND, 0);

// We want the alarm to go off 30 seconds from now.
long firstTime = SystemClock.elapsedRealtime();
firstTime += 30*1000;
long a=c.getTimeInMillis();

// Schedule the alarm!
AlarmManager am = (AlarmManager)ctx.getSystemService(Context.ALARM_SERVICE);
am.setRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP,
c.getTimeInMillis(), 1*60*60*1000, sender);


It is not executed at 23:22h. What I am doing wrong? I noticed firstTime and c.getTimeInMillis() differs a lot in size and length. When I use firstTime, so when set to 30 seconds, the alarm is executed well.