My Timebar SelectionStart and SelectionEnd are bound to DateTime properties. I also have 2 RadDatePickers bound to those date properties. When I initially load the application, or change the date in the Finish DatePicker, the SelectionEnd date of the TimeBar is off by 1 day. So if I pick 12/2/2015 in the DatePicker for my finish date, the timebar will display its' finish as 12/1/2015. When you drag the SelectionEnd bar, or the entire bar, the dates sync back up, but you can cause the problem again by changing the date in the Finish DatePicker.