Problems adding Blend behavior to DatePicker

问题

I'm trying to add a Blend behavior to a DatePicker control to bind an MVVM-Light RelayCommand to the DateChanged event like so:

<DatePicker Date="{Binding SelectedDate, Mode=TwoWay}">
    <Interactivity:Interaction.Behaviors>
        <Core:EventTriggerBehavior EventName="DateChanged">
            <Core:InvokeCommandAction Command="{Binding DateChangedCommand, Mode=OneWay}"/>
        </Core:EventTriggerBehavior>
    </Interactivity:Interaction.Behaviors>
</DatePicker>

I'm using the following definitions:

xmlns:Interactivity="using:Microsoft.Xaml.Interactivity"
xmlns:Core="using:Microsoft.Xaml.Interactions.Core"

However, I keep getting the following error:

WinRT information: Cannot add instance of type
'Microsoft.Xaml.Interactions.Core.EventTriggerBehavior' to a collection of type 
'Microsoft.Xaml.Interactivity.BehaviorCollection'.

I have successfully used Blend behaviors in this way many other times in my project (and with other controls in the same Xaml file) to bind an event to a command, and the DatePicker control is the only one that has thrown an error. Is there another way to accomplish this or are WinRT DatePickers limited in this way?

来源：https://stackoverflow.com/questions/24309546/problems-adding-blend-behavior-to-datepicker