The default value of RangeMaxDate of RadCalendar is "12-30-2099". Because of this you can see only up to 30 days in December 2099. If you want to change the RangeMaxDate try setting RangeMaxDate to a greater value.
I am logging it in our tracking system and our developers will have the care to fix it. As appreciation for reporting us the issue I updated your Telerik points.
Kind regards,
Milena
the Telerik team
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