在UWP窗口10中，列表视图的上下文菜单未打开

Question

我想为列表视图项设置上下文菜单。所以我添加了上下文菜单，但是单击右键时上下文菜单没有打开。我的事件被调用但后来也没有显示上下文菜单。

我已经读过这样的问题，但没有任何解决方案适合我。

这是我的代码：

<Grid>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="6*" />
                <ColumnDefinition Width="4*" />
            </Grid.ColumnDefinitions>

            <!-- Calendar -->
            <telerikInput:RadCalendar x:Name="uiCalendar" Grid.Column="0" SelectionChanged="uiCalendar_SelectionChanged">

            </telerikInput:RadCalendar>

            <ListView x:Name="uiAppointmentsList" Grid.Column="1" Header="Appointments" RightTapped="uiAppointmentsList_RightTapped"
                                                Background="Transparent"  >

                <ListView.ItemContainerStyle>
                    <Style TargetType="ListViewItem">
                        <Setter Property="HorizontalContentAlignment" Value="Stretch"/>
                    </Style>
                </ListView.ItemContainerStyle>
                <ListView.Resources>
                    <MenuFlyout x:Name="uiMenuFlyout">
                        <MenuFlyout.Items>
                            <MenuFlyoutItem x:Name="uiEdit" Text="Edit" />
                            <MenuFlyoutItem Text="Delete" />
                        </MenuFlyout.Items>
                    </MenuFlyout>
                </ListView.Resources>
                <ListView.ItemTemplate>
                    <DataTemplate>
                        <Grid Height="50" Margin="0,3,0,3">                                                           

                            <Grid.ColumnDefinitions>
                                <ColumnDefinition Width="3*"/>
                                <ColumnDefinition Width="6*"/>
                                <ColumnDefinition />
                            </Grid.ColumnDefinitions>
                            <Grid.RowDefinitions>
                                <RowDefinition/>
                                <RowDefinition/>
                            </Grid.RowDefinitions>                            
                            <TextBlock Text="{Binding StartDate}" HorizontalAlignment="Left" VerticalAlignment="Top" Grid.Column="1" Grid.RowSpan="2" Margin="0,-5,0,0"/>
                            <TextBlock Text="{Binding Subject}" FontWeight="Bold"  Margin="0, -3, 0, -3" Grid.Column="2"/>
                            <TextBlock Grid.Row="1" Text="{Binding Location}" Margin="0, -5, 0, 0" Grid.Column="2"/>
                        </Grid>
                    </DataTemplate>
                </ListView.ItemTemplate>
           </ListView>
     </Grid>

以下是代码中的tapped事件：

private void uiAppointmentsList_RightTapped(object sender, Windows.UI.Xaml.Input.RightTappedRoutedEventArgs e)
    {
        UIElement listView = (UIElement)sender;
        uiMenuFlyout.ShowAt(listView, e.GetPosition(listView));
        var a = ((FrameworkElement)e.OriginalSource).DataContext;
    }

请建议我出错的地方。

谢谢