C＃identity2.0 User.Identity.IsAuthenticated null

Question

我已经创建了一个OAuth服务器，我想登录这个站点。

[HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult LocalLogin(LoginViewModel model)
    {
        if (!ModelState.IsValid)
        {
            return View(model);
        }

        var member = memberService.VaildateMmember(model.UserName, model.Password);
        if (member == null)
        {
            ModelState.AddModelError("", "Account or Password Error!");
            return View(model);
        }

        AuthenticationManager.SignOut(DefaultAuthenticationTypes.ApplicationCookie);

        var claims = new List<Claim>
        {
            new Claim(ClaimsIdentity.DefaultNameClaimType, member.AccountName),
            new Claim(ClaimTypes.Name, member.AccountName),
            new Claim(ClaimTypes.Email, member.Email),
            new Claim(ClaimTypes.NameIdentifier, member.Id.ToString())
        };

        var claimsIdentity = new ClaimsIdentity(
            claims,
            DefaultAuthenticationTypes.ApplicationCookie);

        AuthenticationManager.SignIn(
            new AuthenticationProperties
            {
                IsPersistent = true,
                IssuedUtc = DateTime.UtcNow,
                ExpiresUtc = DateTime.UtcNow.Add(TimeSpan.FromMinutes(30))
            },
            claimsIdentity);

        return RedirectToAction("Index", "Home");
    }

我创建了自己的AuthorizeAttribute。

 protected override bool AuthorizeCore(HttpContextBase httpContext)
    {
        if (httpContext == null)
            return false;

        var user = httpContext.User.Identity;

        if (!user.IsAuthenticated)  //here Always false
            return false;

        //CheckUser
        if (Users.Length > 0 && !Users.Split(',').Contains(user.Name, StringComparer.OrdinalIgnoreCase))
            return false;

        //CheckRole
        if (!IsHasRoles(user))
            return false;

        //CheckScope
        if (!IsHasScope(user))
            return false;

        return true;
    }

我不知道这里有什么问题。 为什么httpContext.User.Identity.IsAuthenticated总是返回false。