I guess overloading in not allowed for index method.
The temporary way is:
public ActionResult Index(string myName)
{
if (String.IsNullOrEmpty(myName))
{
ViewBag.Message = "Hello from Parameter-Less Index Method.";
return View();
}
else
{
ViewBag.Message = "Hello from Parameterized Index Method. <br/>Hello " + myName;
return View();
}
}