To reproduce: RadSchedulerLocalizationProvider.CurrentProvider = new CustomSchedulerLocalizationProvider(); radScheduler1.Appointments.Add(new Appointment(DateTime.Now.AddDays(-5), DateTime.Now.AddDays(-4))); radScheduler1.Appointments.Add(new Appointment(DateTime.Now.AddDays(5), DateTime.Now.AddDays(4))); Workaround: radScheduler1.SchedulerElement.Refresh();