C# IAppBuilder程序集引用的问题

我正在试图找出我不能使用IAppBuilder的原因。我已将许多程序集添加到项目中，但仍然出现错误“找不到类型或命名空间名称'IAppBuilder'，是否缺少using指令或程序集引用？” 我的目标是使用AsterNet库连接Asterisk服务器并创建会议室。我使用的代码是：

 using System;
 using Microsoft.Owin;
 using Owin;
 using System.Net.Http;
 using System.Web.Http;
 using System.Web.Http.Routing;
 using AsterNET;
 using AsterNET.ARI;
 using AsterNET.ARI.SimpleConfExample.REST;
 using Microsoft.AspNet.SignalR.Owin;

 namespace AsterNET.ARI.SimpleConfExample.REST

{
public class Startup
{
    // This code configures Web API. The Startup class is specified as a type
    // parameter in the WebApp.Start method.

    public void Configuration(IAppBuilder appBuilder)
    {
        // Configure Web API for self-host. 
        var config = new HttpConfiguration();

        //config.Routes.MapHttpRoute(
        //    name: "DefaultApi",
        //    routeTemplate: "api/{controller}/{id}",
        //    defaults: new { id = RouteParameter.Optional }
        //);

        //config.Routes.MapHttpRoute(
        //    name: "DefaultApiWithAction",
        //    routeTemplate: "api/{controller}/{id}/{action}",
        //    defaults: new { action = "Get" },
        //    constraints: new { HttpCons}
        //);

        config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{controller}/{id}/{action}"
        );

        config.Routes.MapHttpRoute(
            name: "DefaultApiWithId",
            routeTemplate: "api/{controller}/{id}",
            defaults: new { action = "Get" },
            constraints: new { httpMethod = new HttpMethodConstraint(HttpMethod.Get) }
        );

        config.Routes.MapHttpRoute(
            name: "DefaultApiGet",
            routeTemplate: "api/{controller}/",
            defaults: new { action = "Get" },
            constraints: new { httpMethod = new HttpMethodConstraint(HttpMethod.Get) }
        );

        config.Routes.MapHttpRoute(
            name: "DefaultApiPost",
            routeTemplate: "api/{controller}/",
            defaults: new { action = "Post" },
            constraints: new { httpMethod = new HttpMethodConstraint(HttpMethod.Post) }
        );

        config.Routes.MapHttpRoute(
            name: "DefaultApiDelete",
            routeTemplate: "api/{controller}/{id}",
            defaults: new { action = "Delete" },
            constraints: new { httpMethod = new HttpMethodConstraint(HttpMethod.Delete) }
        );
        appBuilder.UseWebApi(config);
    }
} 
}

---

可能重复：我已编辑了您的标题。请看，如果共识是否定的，他们不应该这样做。这不是一个疑问，因为我已经尝试重新安装OWIN，没有解决我的问题。非常感谢。