MVC 4 catch all route never reached

When attempting to create a catch all route in MVC 4 (something I've found several examples of, and based my code on) it returns a 404 error. I'm running this on IIS 7.5. This seems like a straight forward solution, so what am I missing?

One note, if I move the "CatchAll" route above the "Default" route it works. But of course then none of the other controllers are ever reached.

Here is the code:

Route.Config:

        routes.MapRoute(
            name: "Default",
            url: "{controller}/{action}/{id}",
            defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
        );

        routes.MapRoute(
            "CatchAll",
            "{*dynamicRoute}",
            new { controller = "CatchAll", action = "ChoosePage" }
        );

Controller:

public class CatchAllController : Controller
{

    public ActionResult ChoosePage(string dynamicRoute)
    {
        ViewBag.Path = dynamicRoute;
        return View();
    }

}