Hi,
I think you must be sure that you inherits the right model on your .aspx ViewPage code, or maybe your target model is not existing...
Example:
<%@ Page Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<IEnumerable<MvcNW.Models.ProductCategory>>" %>
The above example
MvcNW.Models.ProductCategory must be existing...
Please do not forget to vote if could help...