asp.net-mvc-2 - コントローラーで ActionResult が呼び出されない

Question

コントローラーの ActionResult が呼び出されていません。ブレークポイントを設定すると、ActionResult fileUpload がヒットしていないことが示されます。

以下のビューとコントローラーのコード: (FileUpload.aspx/FileUploadController.cs):

<% using (Html.BeginForm("fileUpload", "FileUpload", 
                FormMethod.Post, new { enctype = "multipart/form-data"  }))
           {%>
        <input type="file" name="file" id="file" />  
        <input type="submit" name="Submit" value="Upload File" />
        <span style="color: red; font-weight: bold">
            <%=TempData["UploadValidationMessage_Failure"]%>
        </span><span style="color: Green; font-weight: bold"> 
            <%=TempData["UploadValidationMessage_Success"]%>
        </span> 
        <%} %>


/// <summary>
    /// n/a
    /// </summary>
    /// <returns>set FileUpload view return value</returns>
    public ActionResult Index()
    {
        return View("FileUpload");
    }

        /// <summary>
        /// Uploads the file and store it in ~\Uploads directory.
        /// </summary>
        /// <returns></returns>
        [AcceptVerbs(HttpVerbs.Post)]
        public ActionResult fileUpload(HttpPostedFileBase file)
        {

            if (file.ContentLength > 0 & isXLSXFile > 0)
            {
                string filePath = Path.Combine(
                  Server.MapPath("~/Uploads"),
                  Path.GetFileName("ExcelFileUpload.xlsx"));  // save as new filename
                try
                {
                    file.SaveAs(filePath);
                    TempData["UploadValidationMessage_Success"] = "File upload succeeded";

                    return View();
                }
                catch (Exception e)
                {
                    TempData["UploadValidationMessage_Failure"] = "Failed to upload the file " + e.ToString();

                        return View();
                    }
                }
                else
                {
                    TempData["UploadValidationMessage_Failure"] = "Filename missing or filename extension is not .xlsx";

                    return View();
                }
    }
    }
public static void RegisterRoutes(RouteCollection routes)
        {
            routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

        routes.MapRoute(
            "Default", // Route name
            "{controller}.aspx/{action}/{id}", // URL with parameters
            new { controller = "Home", action = "Index", id = UrlParameter.Optional } // Parameter defaults
        );

        routes.MapRoute(
          "Root",
          "",
          new { controller = "Home", action = "Index", id = "" }
        );
    }