My issue is that I customer Map Route in MVC which takes three parameters. When I supply all three or just two, the parameters are passed from the URL to my controller. However, when I only supply the first parameter, it is not passed and returns null. Not sure what causes this behavior.

Route:

        routes.MapRoute(
            name: "Details",                                              // Route name
            url: "{controller}/{action}/{param1}/{param2}/{param3}",                           // URL with parameters
            defaults: new { controller = "Details", action = "Index", param1 = UrlParameter.Optional, param2 = UrlParameter.Optional, param3 = UrlParameter.Optional }  // Parameter defaults
         );

Controller:

    public ActionResult Map(string param1, string param2, string param3)
    {

        StoreMap makeMap = new StoreMap();
        var storemap = makeMap.makeStoreMap(param1, param2, param3);
        var model = storemap;
        return View(model);
    }

string param1 returns null when I navigate to:

/StoreMap/Map/PARAM1NAME

but it doesn't return null when I navigate to:

/StoreMap/Map/PARAM1NAME/PARAM2NAME