I am looking to set-up a custom route and custom view model however are getting a null reference error.

I have been using the code based on this previous post

The Route:

var locationRoute = RouteTable.Routes.MapRoute("location", "area/{location}", new { controller = "MyAreas", action = "MyAreas", location = UrlParameter.Optional });  
locationRoute.RouteHandler = new PublishedPageRouteHandler((int)WellKnownPages.MyAreasPublishedPage);

The Handler:

public class PublishedPageRouteHandler : IRouteHandler
    {
        public PublishedPageRouteHandler(int pageId)
        {
            _pageId = pageId;
        }
        private readonly int _pageId;
        private UmbracoHelper _umbraco;
        public UmbracoHelper Umbraco
        {
            get { return _umbraco ?? (_umbraco = new UmbracoHelper(UmbracoContext.Current)); }
        }
        public IHttpHandler GetHttpHandler(RequestContext requestContext)
        {
            //we want to lookup the document by id
            var content = Umbraco.TypedContent(_pageId);
            if (content != null)
            {
                requestContext.RouteData.DataTokens["umbraco"] = new RenderModel(content, CultureInfo.CurrentUICulture);
                UmbracoContext.Current.HttpContext.Items["pageID"] = _pageId;

                var docRequest = UmbracoContext.Current.PublishedContentRequest;//this is null
                requestContext.RouteData.DataTokens.Add("umbraco-doc-request", UmbracoContext.Current.ContentCache.GetById(_pageId)); //required for RenderMvcController
            }
            return new MvcHandler(requestContext);
        }
    }

The Controller:

 public class MyAreasController : RenderMvcController
    {

    public ActionResult MyAreas(RenderModel model, string location)
    {
        return CurrentTemplate(new LocationModel(location));
    }

}

The Model:

 public class LocationModel :  RenderModel
    {
        public string SelectedLocation { get; set; }

        public LocationsModel(string location) : base(UmbracoContext.Current.PublishedContentRequest.PublishedContent)
        {
              SelectedLocation = location;
        }
    }

The exception happens when the model is created as UmbracoContext.Current.PublishedContentRequest.PublishedContent is null.

Any suggestions?