Why is my View not including _Layout.cshtml?

I recently made some changes to my MVC 3 project.

When I run it, the Views dont include any files like Site.css. When I debug my Index() ActionController, it jumps directly to the View, withouting including files like _Layout.cshtml. So i just get a View with a white background, no menus etc.

The Global.asax.cs file contains following code:

public static void RegisterRoutes(RouteCollection routes)
{
    routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

    routes.MapRoute(
        "Default", // Route name
        "{controller}/{action}/{id}", // URL with parameters
        new { controller = "Home", action = "Index", id = UrlParameter.Optional } // Parameter defaults
    );

    routes.MapRoute(
        "Default2", // Route name
        "{controller}/{action}/{id}/{page}", // URL with parameters
        new { controller = "Survey", action = "DisplayQuestions", id = "", page = "" }
    );
}