I have been trying to override the default form submission controller so that we can intercept certain fields, and mask the values being saved (I.e. Credit card information) only to store the last 4 or stop them from beings saved altogether. The information will also be sent to a third party to handle the processing. I have followed the Epi demo but have not had any luck. This will not hit my custom controler no matter what I Do. 

Controller

    [ServiceConfiguration(typeof(IDataSubmitController))]
    public class FormSubmissionController : DataSubmitController
    {
        public ActionResult Index()
        {
            return null;
        }

        public override ActionResult Submit()
        {
            var t = 5;
            return base.Submit();
        }
    }

Initialization Module

 [InitializableModule]
    [ModuleDependency(typeof(EPiServer.Web.InitializationModule))]
    public class SiteInitialization : IConfigurableModule
    {
        public void Initialize(InitializationEngine context)
        {
            GlobalFilters.Filters.Add(new HandleErrorAttribute());

            context.Locate.DisplayChannelService().RegisterDisplayMode(new DefaultDisplayMode(RenderingTags.Mobile)
            {
                ContextCondition = r => r.GetOverriddenBrowser().IsMobileDevice
            });
        }

        public void Uninitialize(InitializationEngine context){}


        public void ConfigureContainer(ServiceConfigurationContext context)
        {
            context.Container.Configure(c =>
            {
                c.For().Use(new FormSubmissionController());
                c.For().Use();
                c.For().Use();
                c.For().Use();
                c.For().Use();
            });

            DependencyResolver.SetResolver(new StructureMapDependencyResolver(context.Container));
            
        }
    }