DI using Unity in MVC Controller is deleting Cookies after redirect

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MVC

C#5.0

cookie

hi
i'm creating an application that have unity framework for dependency injection so my Account Controller is following and that contain Login Action

public class AccountController : Controller
    {

        private readonly IUserService userService;

        public AccountController(IUserService userService)
        {
            this.userService = userService;
        }
        public ActionResult Login()
        {
            return View();
        }

        [HttpPost]
        [AllowAnonymous]
        //[ValidateAntiForgeryToken]
        public ActionResult Login(LoginViewModel model)
        {
            if (ModelState.IsValid)
            {
                string message = "";
                var user = userService.UserExists(model, out message);
                
                if (user != null)
                {
                    CustomPrincipalSerializeModel serializeModel = new CustomPrincipalSerializeModel();
                    serializeModel.UserId = Convert.ToInt32(user.Id);
                    serializeModel.EmailId = user.EmailId;
                    serializeModel.FirstName = user.FirstName;
                    serializeModel.LastName = user.LastName;
                    serializeModel.role = user.Role;

                    string userData = JsonConvert.SerializeObject(serializeModel,Formatting.Indented,
                        new JsonSerializerSettings
                        {
                            PreserveReferencesHandling = PreserveReferencesHandling.Objects
                        });
                    FormsAuthenticationTicket authTicket = new FormsAuthenticationTicket(
                             1,
                            user.EmailId,
                             DateTime.Now,
                             model.RememberMe ? DateTime.Now.AddDays(3) : DateTime.Now.AddHours(3),
                             model.RememberMe ? true : false,
                             userData);
                    
                    string encTicket = FormsAuthentication.Encrypt(authTicket);
                    HttpCookie faCookie = new HttpCookie(FormsAuthentication.FormsCookieName, encTicket);
                    faCookie.Expires = model.RememberMe ? DateTime.Now.AddDays(3) : DateTime.Now.AddHours(3);                    
                    Response.Cookies.Add(faCookie);                    
                    return RedirectToAction("Index", "Home");                    
                }

            }
            else
            {
                ModelState.AddModelError("", "Incorrect username and/or password");
            }
            return View(model);
        }
}

.in login action i'm doing following
1) Checking User Is Existed Or Not if existed then adding FormsAuthentication Cookie .
but when i using IUserService (Interface for DI ) then cookie is deleted when redirect to another action .
2) But If I remove DI from controller then Cookie Is Persisted .

whats wrong i'm finding answer from couple of days .
please give me solution i want DI and Cookie Both .

Thanks in advanced .