I've build a very basic webservice, but I'm having problems accessing it.

 I've followed these instructions to build a MVC service, and followed these instructions to convert it into a web.api service.

This resulted in a project with the following 2 classes:

*** MyServiceRouteMapper.cs:
using DotNetNuke.Web.Api;
namespace innophaseWebService
{
    public class MyServicesRouteMapper : IServiceRouteMapper
    {
        public void RegisterRoutes(IMapRoute routeManager)
        {
            routeManager.MapHttpRoute("innophaseWebService", "default", "{controller}/{action}", new[] { "innophaseWebService" });
        }
    }
}

*** WelcomeController.cs
using DotNetNuke.Web.Api;
namespace innophaseWebService
{
    public class MyServicesRouteMapper : IServiceRouteMapper
    {
        public void RegisterRoutes(IMapRoute routeManager)
        {
            routeManager.MapHttpRoute("innophaseWebService", "default", "{controller}/{action}", new[] { "innophaseWebService" });
        }
    }
}

The ddl file is in the bin folder, so afaik this should work and no other configuration is needed, that I am aware of.

When I visit this (local) url http://dnndev.me/DesktopModules/innop... I get a 404 error.

I'm not sure this is the correct url, it's all bits and pieces put together, but if I understand the instructions correctly, this should be it.
Or maybe the dll fails to load and never registers the url? Is this logged somewhere?