{二逼小青年的记事簿}为什么treelist不会显示子节点的文字？

 <TreeView Name="treeView" DockPanel.Dock="Left" MinWidth="200" >
            <TreeView.ItemTemplate>
                <HierarchicalDataTemplate ItemsSource="{Binding cell}" DataType="{x:Type local:test1}" >
                    <StackPanel Orientation="Horizontal" >
                        <TextBlock VerticalAlignment="Center" Text="{Binding id}"/>
                        <TextBlock VerticalAlignment="Center" Text="{Binding no}"/><!--需要加入这一行才会正确显示子节点 -->
                    </StackPanel>
                </HierarchicalDataTemplate>
            </TreeView.ItemTemplate>
        </TreeView>