我的Global.asax.cs现在看起来像：

public class MvcApplication : System.Web.HttpApplication
    {
        public class Hello
        {
            public string Name { get; set; }
        }

        public class HelloResponse
        {
            public string Result { get; set; }
        }

        public class HelloService : IService<Hello>
        {
            public object Execute(Hello request)
            {
                return new HelloResponse { Result = "Hello," + request.Name };
            }
        }

        public class HelloAppHost : AppHostBase
        {
            //Tell Service Stack the name of your application and where to find your web services
            public HelloAppHost() : base("Hello Web Services",typeof(HelloService).Assembly) { }

            public override void Configure(Container container)
            {
                //register user-defined REST-ful urls
                Routes
                  .Add<Hello>("/hello")
                  .Add<Hello>("/hello/{Name}");
            }
        }


        protected void Application_Start()
        {
            new HelloAppHost().Init();

        }
    }
}

…按照说明.

但是,当我调用Init()方法时,我得到异常：

InvalidDataException: AppHostBase.Instance has already been set

Googling为此提供没有帮助,除了源代码在http://code.google.com/p/servicestack/source/browse/trunk/Common/ServiceStack.Common/ServiceStack.WebHost.Endpoints/AppHostBase.cs?r=1322

看这个,不知何故,实例正在设定.但是怎么样

可能是什么原因造成的？