无法自动添加角色

我的帐户控制器上收到以下错误：

The role 'roleName' was not found.

但我有两个角色管理员和游戏玩家

我的寄存器视图中的下拉列表会选取它们：

   <label for="roleName">Select Role:</label>
    @Html.DropDownList("roleName")
    @Html.ValidationMessage("roleName")

在我的帐户控制器中，我有以下内容：

  //
        // GET: /Account/Register
        [AllowAnonymous]
        public ActionResult Register()
        {
            ViewData["roleName"] = new SelectList(Roles.GetAllRoles(), "roleName");
            return View();
        }
        //
        // POST: /Account/Register
        [HttpPost]
        [AllowAnonymous]
        public ActionResult Register(RegisterModel model)
        {
            if (ModelState.IsValid)
            {
                // Attempt to register the user
                MembershipCreateStatus createStatus;
                Membership.CreateUser(model.UserName, model.Password, model.Email, null, null, true, null, out createStatus);
                if (createStatus == MembershipCreateStatus.Success)
                {
                    Roles.AddUserToRole(model.UserName, "roleName");
                    FormsAuthentication.SetAuthCookie(model.UserName, false /* createPersistentCookie */);
                    return RedirectToAction("Index", "Home");
                }
                else
                {
                    ModelState.AddModelError("", ErrorCodeToString(createStatus));
                }
            }
            // If we got this far, something failed, redisplay form
            return View(model);
        }

我不知道这是为什么高兴？

Roles.AddUserToRole(model.UserName, "roleName");