我可以在Silverlight中声明性地将ItemsContol.ItemsSource绑定到ObservableCollection吗?

我一辈子都搞不懂为什么这样不行。我得到了一个简化的Xaml,如下所示:

<UserControl x:Class="Foo.MainPage" 
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008">
    <Grid x:Name="LayoutRoot">
        <ScrollViewer VerticalAlignment="Stretch" 
                      Background="Black" 
                      HorizontalScrollBarVisibility="Auto" 
                      VerticalScrollBarVisibility="Auto" >
            <ItemsControl x:Name="PictureItemsControl"
                          ItemsSource="{Binding Pics}">
                <ItemsControl.ItemsPanel>
                    <ItemsPanelTemplate>
                        <StackPanel Orientation="Horizontal" 
                                    VerticalAlignment="Center" 
                                    HorizontalAlignment="Center" />
                    </ItemsPanelTemplate>
                </ItemsControl.ItemsPanel>
                <ItemsControl.ItemTemplate>
                    <DataTemplate>
                        <StackPanel>
                            <Image Source="{Binding Location}" 
                                   Height="200" 
                                   Width="200" 
                                   Stretch="UniformToFill" />
                            <TextBlock FontFamily="Verdana" 
                                       FontSize="16" 
                                       Foreground="White" 
                                       Text="{Binding Name}" />
                        </StackPanel>
                    </DataTemplate>
                </ItemsControl.ItemTemplate>
            </ItemsControl>
        </ScrollViewer>
    </Grid>
</UserControl>

在MainPage.xaml的代码隐藏中,我有以下内容:

namespace Foo
{
    public partial class MainPage : UserControl
    {
        public FooViewModel viewModel;

        public MainPage()
        {
            InitializeComponent();
            viewModel = new FooViewModel();
            this.DataContext = viewModel;
        }

    }
}

我的ViewModel如下所示:

namespace Foo
{
    public class FooViewModel:INotifyPropertyChanged
    {
        public ObservableCollection<Pic> Pics;
        public FooViewModel()
        {
            Pics = new ObservableCollection<Pic>();
            Pic.GetPics(Pics);
        }

        //More code here... 
    }
}

Pic只是一个简单的类,它有一些公共属性和一个静态方法,用测试数据填充一个可观察的集合。问题是,我没有看到ItemsControl中发生任何绑定,除非我将这一行添加到我的主页构造函数:

PictureItemsControl.ItemsSource = viewModel.Pics;