How to display en error message as "User Already exist" .

public class AdminController : Controller

{

// GET: Admin

public ActionResult Index()

{

return View();

}

// GET: Admin/Details/5

public ActionResult Registration()

{

return View();

}

[ValidateAntiForgeryToken]

[HttpPost]

public ActionResult Registration(User objNewUser)

{

try

{

using (var context = new CmsDbContext())

{

var chkUser = (from s in context.ObjRegisterUser where s.UserName == objNewUser.UserName || s.EmailId == objNewUser.EmailId select s).FirstOrDefault();

if (chkUser == null)

{

var keyNew = Helper.GeneratePassword(10);

var password = Helper.EncodePassword(objNewUser.Password, keyNew);

objNewUser.Password = password;

objNewUser.CreateDate = DateTime.Now;

objNewUser.ModifyDate = DateTime.Now;

objNewUser.VCode = keyNew;

context.ObjRegisterUser.Add(objNewUser);

context.SaveChanges();

ModelState.Clear();

return RedirectToAction("LogIn", "Login");

}

ViewBag.ErrorMessage = "User Allredy Exixts!!!!!!!!!!";//---this message is not displaying---//

return View();

}

}

catch (Exception e)

{

ViewBag.ErrorMessage = "Some exception occured" + e;

return View();