asp.net mvc . my program is not working .please solve my err

Question

 

when i tried to run it it faces the error like "

CS0161 C# : not all code paths return a value

"  please suggest me the way that it can solve my error

 

 

 

 

[HttpPost]

public ActionResult Create(Student s)

{

if(ModelState.IsValid==true)

{

db.Students.Add(s);

int a = db.SaveChanges();

if (a > 0)

{

//ViewBag.InsertMessage = "<script>alert('Dta Inserted Successfully...!!!')</script>";

TempData["InsertMessage"] = "<script>alert('Dta Inserted Successfully...!!!')</script>";

return RedirectToAction("Index");

}

else

{

ViewBag.InsertMessage = "<script>alert('Dta Not Inserted Successfully...!!!')</script>";

return View();

}

}

}