Change the URL navigation in MVC controller

While I Finishing my job in my main page I have to go to the nest one.
I try to do that from the next page controller lets say `loginController`
While I'm in the main controller I use the following function for this purpose:

Public Sub FlagBtn_Click(ByVal myFlag As String) As ActionResult
            Attributes.envProp._LanguageFlag = myFlag
            Attributes.mvcLogin.Index()
        End Sub

The program goes to the next `loginController` and executes the function there:

<Route("Login")>
       Function Index() As ActionResult
           Return View()
       End Function

Which normally has to change the `url` as well according to the `route file`

routes.MapRoute(
          name:="Default",
          url:="{controller}/{action}/{id}",
          defaults:=New With {.controller = "main", .action = "Index", .id = UrlParameter.Optional}
      )

But that doesn't happen. Instead of that the `url` navigation remains on the `Default` route and of course the next page can't be display.
The question here is how to change the `url` navigation, according to page I choose to go.

What I have tried:

Nothing more than I have already done

Tags: Visual Basic, Javascript, Ajax, MVC4