我的App.xaml.cs中有以下代码片段：
var dict = new ResourceDictionary();
var uri = new Uri("pack://application:,,,/MyAssembly;component/MyDictionary.xaml");
dict.Source = uri;
设置source属性时，我得到一个带有此stacktrace的空指针异常：
bei System.Windows.ResourceDictionary.GetKeyValue(KeyRecord key, IServiceProvider serviceProvider)
bei System.Windows.ResourceDictionary.SetKeys(IList`1 keyCollection, IServiceProvider serviceProvider)
bei System.Windows.ResourceDictionary.SetDeferrableContent(DeferrableContent deferrableContent)
bei System.Windows.Baml2006.WpfSharedBamlSchemaContext.<>c.<Create_BamlProperty_ResourceDictionary_DeferrableContent>b__297_0(Object target, Object value)
bei System.Windows.Baml2006.WpfKnownMemberInvoker.SetValue(Object instance, Object value)
bei MS.Internal.Xaml.Runtime.ClrObjectRuntime.SetValue(XamlMember member, Object obj, Object value)
bei MS.Internal.Xaml.Runtime.ClrObjectRuntime.SetValue(Object inst, XamlMember property, Object value)
bei MS.Internal.Xaml.Runtime.PartialTrustTolerantRuntime.SetValue(Object obj, XamlMember property, Object value)
bei System.Xaml.XamlObjectWriter.Logic_ApplyPropertyValue(ObjectWriterContext ctx, XamlMember prop, Object value, Boolean onParent)
bei System.Xaml.XamlObjectWriter.Logic_DoAssignmentToParentProperty(ObjectWriterContext ctx)
bei System.Xaml.XamlObjectWriter.WriteEndMember()
bei System.Xaml.XamlWriter.WriteNode(XamlReader reader)
bei System.Windows.Markup.WpfXamlLoader.TransformNodes(XamlReader xamlReader, XamlObjectWriter xamlWriter, Boolean onlyLoadOneNode, Boolean skipJournaledProperties, Boolean shouldPassLineNumberInfo, IXamlLineInfo xamlLineInfo, IXamlLineInfoConsumer xamlLineInfoConsumer, XamlContextStack`1 stack, IStyleConnector styleConnector)
bei System.Windows.Markup.WpfXamlLoader.Load(XamlReader xamlReader, IXamlObjectWriterFactory writerFactory, Boolean skipJournaledProperties, Object rootObject, XamlObjectWriterSettings settings, Uri baseUri)
bei System.Windows.Markup.WpfXamlLoader.LoadBaml(XamlReader xamlReader, Boolean skipJournaledProperties, Object rootObject, XamlAccessLevel accessLevel, Uri baseUri)
bei System.Windows.Markup.XamlReader.LoadBaml(Stream stream, ParserContext parserContext, Object parent, Boolean closeStream)
bei System.Windows.Application.LoadBamlStreamWithSyncInfo(Stream stream, ParserContext pc)
bei MS.Internal.AppModel.AppModelKnownContentFactory.BamlConverter(Stream stream, Uri baseUri, Boolean canUseTopLevelBrowser, Boolean sandboxExternalContent, Boolean allowAsync, Boolean isJournalNavigation, XamlReader& asyncObjectConverter)
bei MS.Internal.AppModel.MimeObjectFactory.GetObjectAndCloseStream(Stream s, ContentType contentType, Uri baseUri, Boolean canUseTopLevelBrowser, Boolean sandboxExternalContent, Boolean allowAsync, Boolean isJournalNavigation, XamlReader& asyncObjectConverter)
bei System.Windows.ResourceDictionary.set_Source(Uri value)
bei System.Windows.Baml2006.WpfSharedBamlSchemaContext.<>c.<Create_BamlProperty_ResourceDictionary_Source>b__342_0(Object target, Object value)
bei System.Windows.Baml2006.WpfKnownMemberInvoker.SetValue(Object instance, Object value)
bei MS.Internal.Xaml.Runtime.ClrObjectRuntime.SetValue(XamlMember member, Object obj, Object value)
bei MS.Internal.Xaml.Runtime.ClrObjectRuntime.SetValue(Object inst, XamlMember property, Object value)
bei MS.Internal.Xaml.Runtime.PartialTrustTolerantRuntime.SetValue(Object obj, XamlMember property, Object value)
bei System.Xaml.XamlObjectWriter.Logic_ApplyPropertyValue(ObjectWriterContext ctx, XamlMember prop, Object value, Boolean onParent)
bei System.Xaml.XamlObjectWriter.Logic_DoAssignmentToParentProperty(ObjectWriterContext ctx)
bei System.Xaml.XamlObjectWriter.Logic_AssignProvidedValue(ObjectWriterContext ctx)
bei System.Xaml.XamlObjectWriter.WriteEndMember()
bei System.Xaml.XamlWriter.WriteNode(XamlReader reader)
bei System.Windows.Markup.WpfXamlLoader.TransformNodes(XamlReader xamlReader, XamlObjectWriter xamlWriter, Boolean onlyLoadOneNode, Boolean skipJournaledProperties, Boolean shouldPassLineNumberInfo, IXamlLineInfo xamlLineInfo, IXamlLineInfoConsumer xamlLineInfoConsumer, XamlContextStack`1 stack, IStyleConnector styleConnector)
bei System.Windows.Markup.WpfXamlLoader.Load(XamlReader xamlReader, IXamlObjectWriterFactory writerFactory, Boolean skipJournaledProperties, Object rootObject, XamlObjectWriterSettings settings, Uri baseUri)
bei System.Windows.Markup.WpfXamlLoader.LoadBaml(XamlReader xamlReader, Boolean skipJournaledProperties, Object rootObject, XamlAccessLevel accessLevel, Uri baseUri)
bei System.Windows.Markup.XamlReader.LoadBaml(Stream stream, ParserContext parserContext, Object parent, Boolean closeStream)
bei System.Windows.Application.LoadBamlStreamWithSyncInfo(Stream stream, ParserContext pc)
bei MS.Internal.AppModel.AppModelKnownContentFactory.BamlConverter(Stream stream, Uri baseUri, Boolean canUseTopLevelBrowser, Boolean sandboxExternalContent, Boolean allowAsync, Boolean isJournalNavigation, XamlReader& asyncObjectConverter)
bei MS.Internal.AppModel.MimeObjectFactory.GetObjectAndCloseStream(Stream s, ContentType contentType, Uri baseUri, Boolean canUseTopLevelBrowser, Boolean sandboxExternalContent, Boolean allowAsync, Boolean isJournalNavigation, XamlReader& asyncObjectConverter)
bei System.Windows.ResourceDictionary.set_Source(Uri value)
bei System.Windows.Baml2006.WpfSharedBamlSchemaContext.<>c.<Create_BamlProperty_ResourceDictionary_Source>b__342_0(Object target, Object value)
bei System.Windows.Baml2006.WpfKnownMemberInvoker.SetValue(Object instance, Object value)
bei MS.Internal.Xaml.Runtime.ClrObjectRuntime.SetValue(XamlMember member, Object obj, Object value)
bei MS.Internal.Xaml.Runtime.ClrObjectRuntime.SetValue(Object inst, XamlMember property, Object value)
bei MS.Internal.Xaml.Runtime.PartialTrustTolerantRuntime.SetValue(Object obj, XamlMember property, Object value)
bei System.Xaml.XamlObjectWriter.Logic_ApplyPropertyValue(ObjectWriterContext ctx, XamlMember prop, Object value, Boolean onParent)
bei System.Xaml.XamlObjectWriter.Logic_DoAssignmentToParentProperty(ObjectWriterContext ctx)
bei System.Xaml.XamlObjectWriter.Logic_AssignProvidedValue(ObjectWriterContext ctx)
bei System.Xaml.XamlObjectWriter.WriteEndMember()
bei System.Xaml.XamlWriter.WriteNode(XamlReader reader)
bei System.Xaml.XamlServices.Transform(XamlReader xamlReader, XamlWriter xamlWriter, Boolean closeWriter)
bei System.Xaml.XamlServices.Transform(XamlReader xamlReader, XamlWriter xamlWriter)
bei System.Windows.SystemResources.ResourceDictionaries.LoadDictionary(Assembly assembly, String assemblyName, String resourceName, Boolean isTraceEnabled)
bei System.Windows.SystemResources.ResourceDictionaries.LoadGenericDictionary(Boolean isTraceEnabled)
bei System.Windows.SystemResources.FindDictionaryResource(Object key, Type typeKey, ResourceKey resourceKey, Boolean isTraceEnabled, Boolean allowDeferredResourceReference, Boolean mustReturnDeferredResourceReference, Boolean& canCache)
bei System.Windows.SystemResources.FindResourceInternal(Object key, Boolean allowDeferredResourceReference, Boolean mustReturnDeferredResourceReference)
bei System.Windows.FrameworkElement.FindResourceInternal(FrameworkElement fe, FrameworkContentElement fce, DependencyProperty dp, Object resourceKey, Object unlinkedParent, Boolean allowDeferredResourceReference, Boolean mustReturnDeferredResourceReference, DependencyObject boundaryElement, Boolean isImplicitStyleLookup, Object& source)
bei System.Windows.StaticResourceExtension.FindResourceInAppOrSystem(IServiceProvider serviceProvider, Boolean allowDeferredReference, Boolean mustReturnDeferredResourceReference)
bei System.Windows.StaticResourceExtension.FindResourceInEnviroment(IServiceProvider serviceProvider, Boolean allowDeferredReference, Boolean mustReturnDeferredResourceReference)
bei System.Windows.StaticResourceExtension.TryProvideValueInternal(IServiceProvider serviceProvider, Boolean allowDeferredReference, Boolean mustReturnDeferredResourceReference)
bei System.Windows.ResourceDictionary.SetOptimizedStaticResources(IList`1 staticResources, IServiceProvider serviceProvider, StaticResourceExtension staticRes...
任何想法都出错了？正确引用了程序集。