Thank you for writing.
In order to handle null values in the RadMaskedEditBox, it is more appropriate to use the Value property than the Text property. However, this control does not have built-in support of null values - setting the Value property or the Text to null will lead to unexpected behavior.
A control that is more suitable for your scenario is RadDateTimePicker control. RadDateTimePicker is the control used for handling dates using calendar, spin editing behavior and built-in mask box. RadDateTimePicker offers all the capabilities of the RadMaskedEditBox in scenarios where dates are handled. It offers full null date support, including cases where you receive a null value from the database. It adds additional features, including parsing of various date time formats.
Finally, if you want to have an appearance like that of the RadMaskedEditBox, you can achieve it by hiding the drop down.
If you need additional information, please contact us again.
the Telerik team