为什么我在EF 6中获得System.Data.Entity.ModelConfiguration.ModelValidationException

Question

我的模型定义如下：

{
        [Key]
        [DatabaseGenerated (DatabaseGeneratedOption.None)]
        //[HiddenInput(DisplayValue = false)]
        public string ODID { get; set; }
        [Required(ErrorMessage = "Введите ИНН")]
        public long AuthorityINN { get; set; }
        public int AuthorityID { get; set; }
        [Required(ErrorMessage = "Введите наименование набора данных")]
        public string Name { get; set; }
        [Required(ErrorMessage = "Введите краткое описание")]
        public string Description { get; set; }
        [DataType(DataType.MultilineText)]
        [Required(ErrorMessage = "Введите полное описание")]
        public string FullDescription { get; set; }
        public int CategoryID { get; set; }
        public bool IsPublished { get; set; }
        //public int OwnerID {get;set;}
        public Periodicity Periodicity { get; set; }
        public string KeyWords { get; set; }
        public int UserID { get; set; }
        public DateTime CreateDate { get; set; }
        public bool HasGeo { get; set; }
        public long Reviews { get; set; }
        public long Downloads { get; set; }
}

但是我抓住了一个System.Data.Entity.ModelConfiguration.ModelValidationException异常并带有一条消息：

  

定义此EntityType的键。

可能是什么问题？