In EditAppointmentDialog, if the user tries to create an invalid recurrence pattern, the Ok button is not updating its state to disabled immediately ( it is updated when the dialog is moved). This also affects another scenario described below: 1. Using RadScheduleView (WPF), create an appointment with a duration of 27 hours 2. Close the Edit Appointment dialog to see the appointment created properly in the calendar. 3. Double-click the appointment you just created, to edit it. 4. Click the Edit Recurrence button 5. Change from Weekly to Daily (note that the OK button is now disabled) 6. Change the duration from 27 hours to 3 hours OK button is still disabled If I do it in the opposite order, change the duration to 3 hours and then the recurrence pattern the OK button is enabled. Available in LIB version 2015.2.817, it will be also available in the 2015 Q3 Release.