If your current time is 9:30 AM and you have an appointment in 11:00 AM with reminder 6 hours, the alarm popup should be displayed at 5:00 AM. When you run the application and show the scheduler, the reminder pop up appears immediately. This behavior is expected. However, if you snooze the event with 1 hour, it is expected that the reminder for this appointment will not popup the next hour. However, the RadScheduler makes the following calculation: reminder start time - reminder value + snooze time = 11:00 - 6 + 1 = 6:00. Hence, the reminder popup shows immediately as the current time is 9:30h.