WP7 - 文本菜單列表框項單擊事件

說我有以下數據模板：WP7 - 文本菜單列表框項單擊事件

<DataTemplate x:Key="ItemTemplate"> 
     <StackPanel> 
      <Grid Height="95" Width="446" HorizontalAlignment="Left" ShowGridLines="false" RenderTransformOrigin="0.3,0.526"> 
       <Grid.RowDefinitions> 
        <RowDefinition Height="100"/> 
       </Grid.RowDefinitions> 
       <Grid.ColumnDefinitions> 
        <ColumnDefinition Width="100"/> 
        <ColumnDefinition Width="200"/> 
       </Grid.ColumnDefinitions> 
       <Image Source="{Binding categoryimage}" Height="100" Grid.Row="0" Grid.Column="0" /> 
       <TextBlock Text="{Binding categoryname}" Grid.Row="0" Grid.Column="1" VerticalAlignment="Center" Margin="8,0,-46,0" FontSize="26.667"/> 
       <toolkit:ContextMenuService.ContextMenu> 
        <toolkit:ContextMenu Name="MyContextMenu"> 
         <toolkit:MenuItem Header="Delete console" Click="contextMenuAction_Click"/> 
        </toolkit:ContextMenu> 
       </toolkit:ContextMenuService.ContextMenu> 
      </Grid> 
     </StackPanel> 
    </DataTemplate>

我要的是點擊右鍵菜單項時處理。我將如何訪問列表項目作爲一類對象（如果這是有道理的？）

我嘗試下面的代碼，但它給了我一個NullReferenceException異常：

Private Sub contextMenuAction_Click(sender As System.Object, e As System.Windows.RoutedEventArgs) 

    Dim c As classes.consoles = listBoxview.SelectedItem 
    MessageBox.Show(c.categoryname) 

End Sub

enter image description here