MVC验证强类型视图

我有以下ViewModel:

    public IEnumerable<SelectListItem> SelectAdminsInGroup { get; set; }
    public IEnumerable<SelectListItem> SelectAdminsNotInGroup { get; set; }
    public model.Admin Admin { get; set; }

管理类:

{ 公共管理() { 这个。用户名= 字符串。空; }

    public virtual int AdminId { get; set; }

    [Required(ErrorMessage = "Field 'Username' is required"), StringLength(20, ErrorMessage = "Field 'Username' must be less than 20 characters long")]
    public virtual string Username { get; set; }
    public virtual string Oldusername { get; set; }

    [ValidatePasswordLength()]
    public virtual string Password { get; set; }
    public virtual string ConfirmPassword { get; set; }


    public virtual ICollection<AdminGroup> AdminGroup { get; set; }
}

由于某些原因,PropertiesMustMatch从不在验证摘要中显示错误消息。我还注意到其中一个ModelState键包含“PropertiesMustMatchAttribute”的“Admin”,它应该为空,因为这将是类/摘要错误消息。 如何验证自定义模型? 谢谢