La luz MVVM ha sido un placer aprender, pero aquí estoy atascado. El problema es el disparo de eventos.

En el siguiente código, un botón funciona y dispara eventos. El otro botón no. No se informan errores de enlace en la salida. ¿Hay algo obvio que me estoy perdiendo?

<Grid x:Name="LayoutRoot">...
<StackPanel>
  <Button Content="THIS BUTTON WORKS">
    <i:Interaction.Triggers>
      <i:EventTrigger EventName="Click">
        <Command:EventToCommand Command="{Binding DataContext.HandleAddQuestionActionCommand, ElementName=LayoutRoot, Mode=OneWay}" PassEventArgsToCommand="True"/>
      </i:EventTrigger>
    </i:Interaction.Triggers>
  </Button>
  <sdk1:DataGrid ItemsSource="{Binding QuestionActions}" AutoGenerateColumns="False" >
    <sdk1:DataGrid.Columns>
      <sdk1:DataGridTextColumn Binding="{Binding Answer.Name}" Header="Answer"/>
        <sdk1:DataGridTemplateColumn Header="Edit">
          <sdk1:DataGridTemplateColumn.CellTemplate>
            <DataTemplate>
              <Button Content="THIS BUTTON DONT WORK" >
                <i:Interaction.Triggers>
                  <i:EventTrigger EventName="Click">
                    <Command:EventToCommand Command="{Binding DataContext.HandleEditQuestionActionCommand, ElementName=LayoutRoot, Mode=OneWay}" PassEventArgsToCommand="True"/>
                  </i:EventTrigger>
                </i:Interaction.Triggers>
              </Button>
            </DataTemplate>
          </sdk1:DataGridTemplateColumn.CellTemplate>
        </sdk1:DataGridTemplateColumn>
    </sdk1:DataGrid.Columns>
  </sdk1:DataGrid>
</StackPanel>

Código de modelo de vista:

public RelayCommand<RoutedEventArgs> HandleAddQuestionActionCommand {
    get; private set;
}
public RelayCommand<RoutedEventArgs> HandleEditQuestionActionCommand {
    get; private set;
}


HandleAddQuestionActionCommand = new RelayCommand<RoutedEventArgs>(e =>{...});
HandleEditQuestionActionCommand = new RelayCommand<RoutedEventArgs>(e =>{...});