title: Response.cookies.add seems to not add cookie
body: <p>So I have an authentication method
  which looks like the following</p>
  
  <pre><code> public ActionResult SignIn( SignInModel model, string returnUrl )
          {
              if ( ModelState.IsValid )
              {
                  var user = accountService.Authenticate(model.UserName, model.Password);
                  if ( user != null)
                  {
                      var cookie = ApplicationHelpers.SetupFormsAuthTicket( user, model.RememberMe );
  
                      Response.Cookies.Add(cookie);
  
                      if ( Url.IsLocalUrl( returnUrl ) &amp;&amp; returnUrl.Length &gt; 1 &amp;&amp; returnUrl.StartsWith( "/" )
                          &amp;&amp; !returnUrl.StartsWith( "//" ) &amp;&amp; !returnUrl.StartsWith( "/\\" ) )
                      {
                          return Redirect( returnUrl );
                      }
                      else
                      {
                          return Redirect("/" );
                      }
                  }
                  else
                  {
                      ModelState.AddModelError( "", "The user name or password provided is incorrect." );
                  }
              }
              return View( model );
          }
  </code></pre>
  
  <p>It gets hit as expected.</p>
  
  <p>when the user has successfully authenticated it redirects to another url and the Globab.asax (Application_Postauthenticaterequest) gets hit.
  my problem is that </p>
  
  <pre><code> HttpCookie authCookie = Request.Cookies[ FormsAuthentication.FormsCookieName ];
  </code></pre>
  
  <p>is always null.</p>
  
  <p>I'm creating the cookie in the following 2 methods</p>
  
  <pre><code>public static HttpCookie SetupFormsAuthTicket( OutsourcingPrincipal user, bool isPersistent = false )
          {
              string encTicket = SetupFormsCookie( user, isPersistent );
              return new HttpCookie( FormsAuthentication.FormsCookieName, encTicket );
          }
  
          private static string SetupFormsCookie(  OutsourcingPrincipal user, bool isPersistent )
          {
              var serializeModel = new OutSourcingPrincipalSerializeModel();   
              serializeModel.FirstName = user.FirstName;
              serializeModel.LastName = user.LastName;
              serializeModel.Username = user.Username;
              JavaScriptSerializer serializer = new JavaScriptSerializer();
              string userData = serializer.Serialize( serializeModel );
  
              var ticket = new FormsAuthenticationTicket( 1,
                                                      user.Username,
                                                      DateTime.Now,
                                                      DateTime.Now.AddMinutes(30),
                                                      isPersistent,
                                                      userData );
              var encTicket = FormsAuthentication.Encrypt( ticket );
              return encTicket;
          }
  </code></pre>
  
  <p>Can you spot what i'm doing wrong?</p>