El paquete personalizado en MVC 4 no se procesa

Estoy trabajando en ASP.NET MVC 4 application. I want to make my own bundle containing .js files which I will use for validation but for some reason it's not working. Just to mention - if I render all my scripts in a given view everything is working fine like:

@Scripts.Render("~/Scripts/jquery-1.7.1.min.js")
@Scriptes.Render("~/Scripts/jquery.validate.min.js")
//..few more files

but I don't want to include all those scripts each time so I decided to make my own bundle. The steps I made are:

• In BundleConfig.cs Tengo esto :

public static void RegisterBundles(BundleCollection bundles)

{

//The defaults bundles

bundles.Add(new ScriptBundle("~/bundles/customval").Include(

    "~/Scripts/jquery-1.7.1.min.js",
    "~/Scripts/jquery.validate.min.js",
    "~/Scripts/jquery.unobtrusive-ajax.min.js",
    "~/Scripts/jquery.validate.unobtrusive.min.js"));

}

Entonces reviso mi Global.asax where I have this :

BundleConfig.RegisterBundles(BundleTable.Bundles);

and then in my view I just try :

@Scripts.Render("~/bundles/customval")

y FireBug is saying that no JavaScript is load for this page.

I use custom _Layout page and I wonder if I have to add something there. I added:

@RenderSection("scripts", required: false)

en mi _Layout but it doesn't seem to solve something. So what am I missing to make my bundles working?