WPF ItemsControl:似乎无法获取要在视图中显示的项目

我正在处理的代码是WPF应用程序的一部分,它应该显示一组用户可以交互的扑克牌。我正在使用三个用户控件:

• 主控
• 卡片堆垛控制

在MainControl.xaml中:

    <StackPanel 
        Grid.Row="0"
        Orientation="Horizontal">
        <ItemsControl 
            ItemsSource="{Binding Path=CardStacks}"
            >
            <ItemsPanelTemplate>
                <StackPanel Orientation="Horizontal" />
            </ItemsPanelTemplate>
        </ItemsControl>
    </StackPanel>

我的数据模板在Resources.xaml文件中定义:

<DataTemplate x:Key="MainTemplate" DataType="{x:Type ViewModel:MainViewModel}">
    <View:MainControl />
</DataTemplate>

<DataTemplate DataType="{x:Type ViewModel:CardStackViewModel}">
    <View:CardStackControl />
</DataTemplate>

<DataTemplate x:Key="CardTemplate" DataType="{x:Type ViewModel:CardViewModel}">
    <View:CardControl />
</DataTemplate>

CardStackControl.xaml:

<StackPanel Orientation="Vertical">
    <TextBlock 
        Height="30"
        HorizontalAlignment="Center"
        VerticalAlignment="Center"
        Text="{Binding Path=CardName}" 
        />
    <ItemsControl
        Height="Auto"
        ItemsSource="{Binding Path=Cards}"
        ItemTemplate="{StaticResource CardTemplate}"
        >
        <ItemsPanelTemplate>
            <StackPanel Orientation="Horizontal" />
        </ItemsPanelTemplate>
    </ItemsControl>
    <TextBlock 
        Height="30"
        HorizontalAlignment="Center"
        VerticalAlignment="Center"
        Text="{Binding Path=Count}" 
        />
</StackPanel>

CardControl.xaml:

    <TextBlock 
        Name="TitleTextBlock"
        Grid.Row="0" 
        Grid.Column="1"                   
        HorizontalAlignment="Center"                   
        VerticalAlignment="Center"
        Text="{Binding Path=Name}"
        >     

MainViewModel:

public ObservableCollection<CardStackViewModel> CardStacks;

// ...

CardStackViewModel:

public class CardStackViewModel
{
    private CardStack Model;

    public string CardName
    {
        get
        {
            return this.Model.CardType.Name;
        }
    }

    public int Count
    {
        get
        {
            return this.Model.Cards.Count;
        }
    }

    public ObservableCollection<CardViewModel> Cards { get; private set; }

    // ...

CardViewModel:

    /// <summary>
    /// A reference to the Card type.
    /// </summary>
    private Card Model;

    /// <summary>
    /// Retrieves the name of the card.
    /// </summary>
    public string Name
    {
        get
        {
            return this.Model.CardType.Name;
        }
    }

    public string Caption
    {
        get
        {
            return this.Model.CardType.Text;
        }
    }

    // ...

在MainViewModel、CardStackViewModel构造函数中,两个ObservableCollection实例都被初始化、填充并填充一些测试数据。

当我加载应用程序并创建MainViewModel时,UserControls不会显示,测试数据也不可见。我正在使用 this tutorial 作为指导,使MainViewModel对应于该窗口中选项卡控件上的“工作空间”ViewModel。当然,这个例子应该水平地布局每个控件,现在还可以——我还在学习WPF。