关于C#的Uri的问题，请高手帮忙

Question

using System;
using System.IO;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Markup;namespace Petzold.LoadXamlResource
{
    public class LoadXamlResource : Window
    {
        [STAThread]
        public static void Main()
        {
            Application app = new Application();
            app.Run(new LoadXamlResource());
        }
        public LoadXamlResource()
        {
            Title = "Load Xaml Resource";            Uri uri = new Uri("pack://application:,,,/LoadXamlResource.xml");
            Application.GetResourceStream(uri);
            Stream stream = Application.GetResourceStream(uri).Stream;
            FrameworkElement el = XamlReader.Load(stream) as FrameworkElement;
            Content = el;            Button btn = el.FindName("MyButton") as Button;            if (btn != null)
                btn.Click += ButtonOnClick;
        }
        void ButtonOnClick(object sender,RoutedEventArgs args)
        {
            MessageBox.Show("The button labeled '" +
                            (args.Source as Button).Content +
                            "' has been clicked");
        }
    }
}以上这段代码，运行到“Stream stream = Application.GetResourceStream(uri).Stream;”的时候报NullReferenceException，请问大神们什么原因，QQQ

Answer 1

加断点，判断Application或Application.GetResourceStream(uri)哪个是空