From my point of view the RadDatePicker misinterprets date entries in ISO 8601 format.
The result of DateTime.Parse("2013-11-12") is "12. November 2013" for every culture setting (correct).
If i enter "2013-11-12" (yyyy-mm-dd) into the RadDatePicker textbox the result is "11. Dezember 2013" (wrong).
It should be possible to enter a date in the culture specific notation as well as according to ISO standard.
Regards,
Andreas
It is good to have in mind that these date format patterns are case-sensitive. The following link shows all of the valid patterns for RadControls: http://www.telerik.com/help/aspnet-ajax/calendar-date-format-pattern.html. In addition in your example if you replace the "mm" with "MM" you can verify that ISO 8601 is fully supported by the RadDatePicker.