我正在开发 WPF 桌面应用程序，我在我的 xaml 设计器预览中收到此错误。我已经浏览了许多链接，但无法弄清楚。
之前也有人提出过同样的问题。URI 的未知资源，但是我仍然无法解决它。我还在下面附上了图片。
这是完整的错误：
Exception: The component 'Microsoft.Expression.Utility.ValueEditors.SplitComboBox' does not have a resource identified by the URI '/Microsoft.Expression.Utility;component/valueeditors/splitcombobox.xaml'.
而且，我正面临警告信息。
Warning 7 There was a mismatch between the processor architecture of the project being built "MSIL" and the processor architecture of the reference "Microsoft.Expression.Utility, Version=5.0.30709.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=x86", "x86". This mismatch may cause runtime failures. Please consider changing the targeted processor architecture of your project through the Configuration Manager so as to align the processor architectures between your project and references, or take a dependency on references with a processor architecture that matches the targeted processor architecture of your project. Predictions Version 1
为了解决上述警告，我浏览了这个链接，但都是徒劳的。
程序运行良好，但我需要实施设计更改并观察更改，我必须一次又一次地运行程序，因为设计预览不起作用。
另请注意，当我包含mahapps.metro库时，它开始发生。如果需要，我可以粘贴我的.xaml文件。我正在使用VS2012。提前致谢。