I'm working with a somewhat older version of the Telerik controls (2011 Q3), but I would think this would still work. I have the control setup to use DatePicker for the InputMode. If I click on the calendar and navigate to some date and click on it, then the calendar disappears, but the date I selected isn't in the control. Checking the control's SelectedValue, it is null, so it didn't accept the date I clicked upon, either.
I'm guessing that I'm doing something wrong, have left out something in the XAML, or something. Here's the relevant XAML: