Custom WPF Control does not update on Focus Lost

I implemented an adapation of Infragistics XamDateTimeEditor which does not force me to use an Edit Mask. When I enter a date by keyboard the Value is updated correctly, however when I select a date from the drop down MonthCalendar, the new开发者_如何学Python date is displayed in the control, but the value is not updated in the ViewModel that binds to the control.

Does anyone know what to look for to correct this?

Any help is appreciated.

Make sure the UpdateSourceTrigger for your Binding is set correctly. (LostFocus or PropertyChanged) To make sure your Binding is working correct, you can take a look at this article