Thank you for writing.
Could you be more specific about the method you use to pick a date? Is it using the dropdown calendar, the up/down arrows to spin the values, via the mouse wheel scrolling up and down or typing in the mask edit field of RadDateTimePicker?
If you have different culture settings, the display dates would differ from one another as RadDateTimePicker uses the current culture specified by the OS by default. If you want to select a different culture, you should use the Culture property. This will cause the RadDateTimePicker value to re-format itself based on the new culture setting.
If you type slowly, for example you enter 200 in the year field of RadDateTimePicker,
and then wait for 0.5 seconds, an auto-update will happen and the value would be updated to the minimum possible value, which in this case is the MinDate. We will expose a property which controls the time-delay for auto-update in the next release.
If you have any other questions, do not hesitate to write me back.
the Telerik team