{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>