Error 401.2: Unauthorized: Logon failed due to server configuration

We have used Microsoft.AspNet.FriendlyUrls for that we install from nuget package manager and added following code into Global.ASAX file.

protected void Application_Start(object sender, EventArgs e)
{
RouteConfig.RegisterRoutes(RouteTable.Routes);
}

 public static void RegisterRoutes(RouteCollection routes)
        {
            var settings = new FriendlyUrlSettings();
            settings.AutoRedirectMode = RedirectMode.Permanent;
            routes.EnableFriendlyUrls(settings);
        }

This is working fine onto localhost but after publishing on to IIS 8.0 server the following error :

Note: Our Application Authentication Mode is  authentication mode="Forms"

Access is denied.

Description: An error occurred while accessing the resources required to serve this request. The server may not be configured for access to the requested URL.
Error message 401.2.: Unauthorized: Logon failed due to server configuration. Verify that you have permission to view this directory or page based on the credentials you supplied and the authentication methods enabled on the Web server. Contact the Web server’s administrator for additional assistance.

I searched for this issue onto different forum but i did not found the solution. kindly help me