带有wpf的TextBlock工具提示问题

Question

我有一个带有TextBlock的网格。我试图在TextBlock上显示工具提示（特别是如果通过CharacterEllipsis修剪块的文本时显示全文），但是当我将鼠标悬停在文本块上时，工具提示不会出现。有什么想法吗？

<DataTemplate x:Key="UnjoinedLampTemplate" DataType="{x:Type devices:DeviceViewModel}">
        <Grid Width="133.2"
              Margin="0,10,0,10"
              Cursor="Hand"
              HorizontalAlignment="Center" VerticalAlignment="Top">
            <Grid.RowDefinitions>
                <RowDefinition Height="80" />
                <RowDefinition Height="25" />
            </Grid.RowDefinitions>
            <Border x:Name="DisplayColor" Grid.Row="0"
                    Width="70" Height="70"
                    CornerRadius="100"
                    Background="#54de61" />
            <Image Stretch="Uniform" Grid.Row="0"
                   Width="70" Height="70"
                   Source="path_to_component" />
            <Border x:Name="textDisplay" Grid.Row="0"
                    Visibility="Visible"
                    Background="Black" Opacity=".75"
                    BorderThickness="1" BorderBrush="White"
                    CornerRadius="5"
                    VerticalAlignment="Center" HorizontalAlignment="Center">
                <TextBlock Text="{Binding Label}" Style="{StaticResource DeviceLabelStyle}">
                    <TextBlock.ToolTip>
                        <ToolTip>
                                 <TextBlock Text="my tooltip" />
                        </ToolTip>
                    </TextBlock.ToolTip>
                </TextBlock>

            </Border>
        </Grid>
        <DataTemplate.Triggers>

这是TextBlock中引用的DeviceLabelStyle：

   <Style x:Key="DeviceLabelStyle" TargetType="{x:Type TextBlock}">
        <Setter Property="FontSize" Value="14" />
        <Setter Property="FontFamily" Value="{StaticResource PrimaryFontFamily}" />
        <Setter Property="Margin" Value="5,3,5,3" />
        <Setter Property="Width" Value="100" />
        <Setter Property="Foreground" Value="White" />
        <Setter Property="TextAlignment" Value="Center" />
        <Setter Property="TextTrimming" Value="CharacterEllipsis" />
    </Style>