选择不在html.dropdownlist MVC中工作

Question

我有以下代码

  

person.State是Nullable string

控制器：

ViewBag.States = new List<SelectListItem>
            {
                new SelectListItem {Value = "", Text = "Please select", Selected = string.IsNullOrEmpty(person.State)},
                new SelectListItem {Value = "ACT", Text = "ACT", Selected = person.State.ToLower() == "act"},
                new SelectListItem {Value = "NSW", Text = "NSW", Selected = person.State.ToLower() == "nsw"},
                new SelectListItem {Value = "NT", Text = "NT", Selected = person.State.ToLower() == "nt"},
                new SelectListItem {Value = "QLD", Text = "QLD", Selected = person.State.ToLower() == "qld"},
                new SelectListItem {Value = "SA", Text = "SA", Selected = person.State.ToLower() == "sa"},
                new SelectListItem {Value = "TAS", Text = "TAS", Selected = person.State.ToLower() == "tas"},
                new SelectListItem {Value = "VIC", Text = "VIC", Selected = person.State.ToLower() == "vic"},
                new SelectListItem {Value = "WA", Text = "WA", Selected = person.State.ToLower() == "wa"}
            };

查看：

@{
 List<SelectListItem> states = ViewBag.States;
}
...
...
...
  @Html.DropDownList("State", states, new { id = "State", @class = "roleSelect" })

即使一个SelectListItem为Selected=true，但在输出中它显示Please select。当我在html输出中检查元素时，option都没有Select属性。

有什么建议吗？