Android AlarmManager firing at wrong times

Question

I am setting an alarm with alarm manager to run at 6PM. If it is already 6PM, I want it to run the next day at 6PM.

AlarmManager manager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);

        Calendar calendar = Calendar.getInstance();

        if(calendar.get(Calendar.HOUR_OF_DAY) < 18) {
            calendar.set(Calendar.HOUR, 18);
            calendar.set(Calendar.MINUTE, 0);
        } else {
            // Set sync time
            calendar.add(Calendar.DATE, 1);
            calendar.set(Calendar.HOUR, 18);
            calendar.set(Calendar.MINUTE, 0);
        }       

        Intent alarmIntent = new Intent(context, AlarmReceiver.class);  
        alarmIntent.putExtra("syncmode", "upload");

        PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, alarmIntent, PendingIntent.FLAG_UPDATE_CURRENT);

        manager.set(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), pendingIntent);

I have 6 Android tablets all running the same exact code and some are waking up at the correct times, others are running hours later. I have checked the timezones and everything matches. The documentation for AlarmManager says to use UTC time to set the alarm, but in practice I am using local time and the ones that are working are firing at the correct time. The others are firing 4 hours before time. What am I doing wrong?

Edit: I cannot answer my own question so, I was setting Calendar.HOUR instead of HOUR_OF_DAY which was causing the time to be set incorrectly.

Answer 1

Just so this will be removed from the "Unanswered" list:

I was setting Calendar.HOUR instead of HOUR_OF_DAY which was causing the time to be set incorrectly.