.NET Dropdown无法正确检索

Question

我有以下代码填充下拉列表：

    string strConn = ConfigurationManager.ConnectionStrings["LiSQL"].ConnectionString;

    using (SqlConnection con = new SqlConnection(strConn))
    {
        DataSet ds = new DataSet();
        using (SqlDataAdapter myda = new SqlDataAdapter("SELECT [PostAbbrev], [State] FROM [States]", con))
        {
            myda.Fill(ds);
            ddlState.DataSource = ds;
        }
    }

    ddlState.DataTextField = "State";
    ddlState.DataValueField = "State";
    ddlState.DataBind();

我的下拉代码是这样的：

    <asp:DropDownList ID="ddlState" runat="server" DataTextField="States" DataValueField="States">                                         
    </asp:DropDownList>

当我选择说德克萨斯时，该值仍默认为第一个条目Alabama： 以下是我为检索值所做的工作：

    string state = ddlState.SelectedItem.Text;