MVC3 @Context.User.Identity.Name empty value

当用户按下登录按钮时，控制器中执行以下功能，其中我使用SetAuthCookie:设置用户的名字

// POST: /Account/SignUp
    [HttpPost]
    public ActionResult Index(ConsumerView consumerData)
    {
        try
        {
            ConsumerManager consumerManagerObj = new ConsumerManager();
            if (consumerManagerObj.IsValidUser(consumerData.LoginID, consumerData.Password))
            {
                FormsAuthentication.SetAuthCookie(consumerData.FirstName, false);
                return View ("WelcomeConsumer");
            }
            else
            {
                ModelState.AddModelError("", "Invalid Username/Password!!");
            }
        }
        catch
        {
            return View(consumerData);
        }
        return View(consumerData);
    }

WelcomeConsumer视图具有代码：

@{
ViewBag.Title = "Home";
}
<h2>Welcome</h2>
<h2>Hi <b>@Context.User.Identity.Name</b></h2>
@Html.ActionLink("[Sign Out]", "SignOut", "ConsumerAccount")
<p>
<ul>
    <li>@Html.ActionLink("Book new Ticket", "NewBooking", "ConsumerAccount")</li>
    <li>@Html.ActionLink("View all Bookings", "ViewAllBookings", "ConsumerAccount")    </li>
</ul>
@ViewBag.NewBookingSuccess
</p>

但是@Context.User.Identity.Name总是有空值，有什么解决办法吗？