我正在研究MVC3剃刀项目。我的解决方案正常运行，但现在它正确编译但在运行时显示错误。显示以下错误，请帮我解决。
Expression of type 'System.Web.Mvc.MvcWebRazorHostFactory' cannot be used for return type 'System.Web.WebPages.Razor.WebRazorHostFactory'
来源错误：
An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below