使用带有自定义角色提供程序的asp.net mvc 4登录失败时,错误消息

当我尝试使用不存在的用户帐户登录时,不会显示错误消息.这是我目前的代码.

这是登录的代码：

[HttpPost]
        [AllowAnonymous]
        [ValidateAntiForgeryToken]
        public ActionResult Login(LoginModel model,string returnUrl)
        {
            if (ModelState.IsValid)
            {
                using (SampleDBEntities objContext = new SampleDBEntities())
                {
                    var objUser = objContext.Users.FirstOrDefault(x => x.AppUserName == model.UserName && x.Password == model.Password);
                    if (objUser == null)
                    {
                        ModelState.AddModelError("LogOnError","The user name or password provided is incorrect.");
                    }
                    else
                    {
                        FormsAuthentication.SetAuthCookie(model.UserName,model.RememberMe);

                        if (Url.IsLocalUrl(returnUrl) && returnUrl.Length > 1 && returnUrl.StartsWith("/")
                           && !returnUrl.StartsWith("//") && !returnUrl.StartsWith("/"))
                        {
                            ModelState.AddModelError("LogOnError","The user name or password provided is incorrect.");
                            return Redirect(returnUrl);
                        }
                        else
                        {
                            //Redirect to default page

                            //return RedirectToAction("RedirectToDefault");
                            return RedirectToAction("Index","Home");
                        }
                    }
                }
            }
            // If we got this far,something failed,redisplay form
            return View(model);
        }

以下是提供程序实现的代码：

public class MyRoleProvider : RoleProvider
    {
        public override void AddUsersToRoles(string[] usernames,string[] roleNames)
        {
            throw new NotImplementedException();
        }

        public override string ApplicationName
        {
            get
            {
                throw new NotImplementedException();
            }
            set
            {
                throw new NotImplementedException();
            }
        }

        public override void CreateRole(string roleName)
        {
            throw new NotImplementedException();
        }

        public override bool DeleteRole(string roleName,bool throwOnPopulatedRole)
        {
            throw new NotImplementedException();
        }

        public override string[] FindUsersInRole(string roleName,string usernameToMatch)
        {
            throw new NotImplementedException();
        }

        public override string[] GetAllRoles()
        {
            throw new NotImplementedException();
        }


        public override string[] GetRolesForUser(string username)
        {
            using (SampleDBEntities objContext = new SampleDBEntities())
            {
                var objUser = objContext.Users.FirstOrDefault(x => x.AppUserName == username);
                if (objUser == null)
                {
                    return null;
                }
                else
                {
                    string[] ret = objUser.Roles.Select(x => x.RoleName).ToArray();
                    return ret;
                }
            }
        }

        public override string[] GetUsersInRole(string roleName)
        {
            throw new NotImplementedException();
        }

        public override bool IsUserInRole(string username,string roleName)
        {
            throw new NotImplementedException();
        }

        public override void RemoveUsersFromRoles(string[] usernames,string[] roleNames)
        {
            throw new NotImplementedException();
        }

        public override bool RoleExists(string roleName)
        {
            throw new NotImplementedException();
        }
    }
}

先生/女士,你的答案会有很大的帮助.谢谢