Visual studio 2010 如何为System.Windows（Windows Phone）加载调试符号？

问题是，我正在开发的Windows Phone应用程序出现了一个奇怪的异常：

System.Exception was unhandled
Message=Unspecified error 
StackTrace:
   at MS.Internal.XcpImports.CheckHResult(UInt32 hr)
   at MS.Internal.XcpImports.Collection_AddValue[T](PresentationFrameworkCollection`1 collection, CValue value)
   at MS.Internal.XcpImports.Collection_AddDependencyObject[T](PresentationFrameworkCollection`1 collection, DependencyObject value)
   at System.Windows.PresentationFrameworkCollection`1.AddDependencyObject(DependencyObject value)
   at System.Windows.Controls.UIElementCollection.AddInternal(UIElement value)
   at System.Windows.PresentationFrameworkCollection`1.Add(UIElement value)
   at System.Windows.Controls.ItemsControl.AddVisualChild(Int32 index, DependencyObject container, Boolean needPrepareContainer)
   at System.Windows.Controls.ItemsControl.AddContainerForPosition(GeneratorPosition position)
   at System.Windows.Controls.ItemsControl.OnItemsChangedHandler(Object sender, ItemsChangedEventArgs args)
   at System.Windows.Controls.ItemContainerGenerator.OnItemAdded(Object item, Int32 index)
   at System.Windows.Controls.ItemContainerGenerator.System.Windows.Controls.ICollectionChangedListener.OnCollectionChanged(Object sender, NotifyCollectionChangedEventArgs args)
   at System.Windows.Controls.WeakCollectionChangedListener.SourceCollectionChanged(Object sender, NotifyCollectionChangedEventArgs e)
   at System.Windows.Controls.ItemCollection.NotifyCollectionChanged(NotifyCollectionChangedEventArgs e)
   at System.Windows.Controls.ItemCollection.System.Windows.Controls.ICollectionChangedListener.OnCollectionChanged(Object sender, NotifyCollectionChangedEventArgs e)
   at System.Windows.Controls.WeakCollectionChangedListener.SourceCollectionChanged(Object sender, NotifyCollectionChangedEventArgs e)
   at System.Collections.ObjectModel.ObservableCollection`1.OnCollectionChanged(NotifyCollectionChangedEventArgs e)
   at System.Collections.ObjectModel.ObservableCollection`1.InsertItem(Int32 index, FormItem item)
   at System.Collections.ObjectModel.Collection`1.Add(FormItem item)
   at //My Code

我的代码试图做的是向ObservableCollection添加一个项

我想进入System.Windows代码，以便查看“未指定错误”是什么

我已经在Visual Studio中执行了以下操作：

• 启用.NET Framework源代码单步执行
• 启用源服务器支持
• 启用Microsoft符号服务器

尽管如此，我不能在调用堆栈中插入（双击）任何System.Windows方法

感谢您的帮助。如果你们需要更多的澄清，请告诉我