title: What wrong with this Template
body: <p>I am using DataTrigger to change the DataTemplate based on a enum.</p>
  
  <pre><code>&lt;TreeView &gt;
      &lt;TreeView.Resources&gt;
          &lt;HierarchicalDataTemplate DataType="{x:Type model:Card}" ItemsSource="{Binding Reqs}"&gt;
              &lt;StackPanel VerticalAlignment="Center"&gt;
                  &lt;TextBlock Text="{Binding Label}" FontWeight="Bold" Foreground="Gray" HorizontalAlignment="Stretch" VerticalAlignment="Center" FontSize="15"/&gt;
                  &lt;TextBlock Text="{Binding Reqs.Count}" FontWeight="UltraLight" Foreground="Gray" HorizontalAlignment="Stretch" VerticalAlignment="Center" FontSize="10"/&gt;
              &lt;/StackPanel&gt;
          &lt;/HierarchicalDataTemplate&gt;
  
          &lt;DataTemplate DataType="{x:Type model:ReqCard}"&gt;
              &lt;ContentControl&gt;
                  &lt;ContentControl.Style&gt;
                      &lt;Style TargetType="{x:Type ContentControl}"&gt;
                          &lt;Setter Property="ContentTemplate"&gt;
                              &lt;Setter.Value&gt;
                                  &lt;DataTemplate &gt;
                                      &lt;Border Width="340" Background="LightBlue"&gt;
                                          &lt;Grid Name="PGrid" Margin="5"&gt;
                                              &lt;Grid.ColumnDefinitions&gt;
                                                  &lt;ColumnDefinition Width="*"/&gt;
                                                  &lt;ColumnDefinition Width="Auto"/&gt;
                                              &lt;/Grid.ColumnDefinitions&gt;
                                              &lt;TextBlock Margin="2" Text="{Binding Label}" Foreground="Gray" FontSize="15" FontWeight="Normal"/&gt;
                                              &lt;CheckBox Grid.Column="1" Margin="2" IsChecked="{Binding IsMeet}" Click="IsMeet_OnClick"/&gt;
                                          &lt;/Grid&gt;
                                      &lt;/Border&gt;
                                  &lt;/DataTemplate&gt;
                              &lt;/Setter.Value&gt;
                          &lt;/Setter&gt;
                          &lt;Style.Triggers&gt;
                              &lt;DataTrigger Binding="{Binding DemandType}" Value="{x:Static enums:DemandType.Condition}"&gt;
                                  &lt;Setter Property="ContentTemplate"&gt;
                                      &lt;Setter.Value&gt;
                                          &lt;DataTemplate &gt;
                                              &lt;Border Width="340" Background="LightBlue" &gt;
                                                  &lt;Grid Name="KGrid" Margin="5"&gt;
                                                      &lt;Grid.ColumnDefinitions&gt;
                                                          &lt;ColumnDefinition Width="*"/&gt;
                                                          &lt;ColumnDefinition Width="Auto"/&gt;
                                                      &lt;/Grid.ColumnDefinitions&gt;
                                                      &lt;TextBlock Margin="2" Text="{Binding Label}" Foreground="Gray" FontSize="15" FontWeight="Normal"/&gt;
                                                      &lt;TextBox Grid.Column="1" Width="20" Margin="2" Text="{Binding Condition}" Click="Condition_OnClick"/&gt;
                                                  &lt;/Grid&gt;
                                              &lt;/Border&gt;
                                          &lt;/DataTemplate&gt;
                                      &lt;/Setter.Value&gt;
                                  &lt;/Setter&gt;
                              &lt;/DataTrigger&gt;
                          &lt;/Style.Triggers&gt;
                      &lt;/Style&gt;
                  &lt;/ContentControl.Style&gt;
              &lt;/ContentControl&gt;
          &lt;/DataTemplate&gt;
      &lt;/TreeView.Resources&gt;
  &lt;/TreeView&gt;
  </code></pre>
  
  <p>It displays no data.</p>