Why User is Null?

Hi!

I've got error, need help.
I have MVC project.

Controller:
public class HomeController : Controller
{
public ActionResult Index()
{
return View();
}
}

And view:


<%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<ht ml xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Index</title>
</head>
<body>
<div>
<%= User.Identity.Name %>
</div>
</body>
</html>
When I open host/home/index, I get error  NullReferenceExcep ...