Noob plugin question

Hi I think this is a noob question -

I would like to override functionality in the Admin "ProductReviewController" so I have created my own controller in my plugin called "MyProductReviewController" which is a copy of "ProductReviewController". I have implemented the IRouteProvider with -

var route = routes.MapRoute("Plugin.Admin.MyProductReviewController",
                 "Plugins/ProductReview/List",
                 new { controller = "MyProductReview", action = "List" },
                 new[] { "MyPlugin.Admin.Controllers" }
            );

However when loading the ProductReview page the system will still use the nop ProductReviewController... what have I done wrong??

Remove the "Plugin" from the Route path... woops