Hello Naresh,

The default z-index of RadDateTimePicker popups is 5000.

http://www.telerik.com/help/aspnet-ajax/controlling-absolute-positioning-with-zindex.html

You should either set a higher z-index with the picker's ZIndex property, or set a lower z-index to your modal popup.

If you are using al older RadControls version and do not have a ZIndex property for the pickers, then use one of these:

http://www.telerik.com/community/forums/aspnet-ajax/calendar/datepicker-showing-up-underneath-pop-up-window.aspx#606838

or

http://www.telerik.com/community/forums/aspnet/calendar/raddatepicker-and-modalpopupextender-css-help.aspx#686393

or

http://www.telerik.com/community/forums/aspnet-ajax/calendar/raddatepicker-on-a-modal-popup.aspx#625807


Regards,
Dimo
the Telerik team