C# Updatepanel中的Dropdownlist工作不正常

我在updatepanel中放置了2个Dropdownlist。每当第一个dropdownlist所选索引发生变化时，第二个dropdownlist的项目就会发生变化。（就像国家/地区……在我的例子中是城市区域）

每当我更改第一个dropdownlist（DDLCity1）selectedindex时，它都可以正常工作。但只有两次。 假设，在页面加载后，我选择“LA”没问题，LA区域将加载到另一个dropdownlist区域1中。然后我改变一下，选择“NY”城市，另一个下拉列表也可以

但现在，我尝试第二个下拉列表显示没有变化！！！！！它仍然显示最后的结果

在排序中，回发只工作2次

为了进行测试，我在indexchange的下拉列表中只弹出了2次警报消息。好像只回了2次：（（请帮我

<pre>

 <asp:UpdatePanel ID="UpdatePanel1" runat="server" ViewStateMode="Enabled" UpdateMode="Always">
                                <ContentTemplate>
                                    <asp:DropDownList ID="DDLCity1" runat="server" AutoPostBack="false" OnSelectedIndexChanged="DDLCity_SelectedIndexChanged"
                                        ViewStateMode="Enabled">
                                        <asp:ListItem Text="- All City -" />
                                    </asp:DropDownList>
                                    <asp:DropDownList ID="DDLArea1" runat="server" Style="margin-bottom: 0px" OnSelectedIndexChanged="DDLArea_SelectedIndexChanged"
                                        AutoPostBack="false" ViewStateMode="Enabled">
                                        <asp:ListItem Text="- Anywhere -" />
                                    </asp:DropDownList>
                                    <span style="position: absolute;">
                                        <asp:UpdateProgress ID="UpdateProgress1" runat="server">
                                            <ProgressTemplate>
                                                <img src="img/loading.gif" alt="Alternate Text" />
                                            </ProgressTemplate>
                                        </asp:UpdateProgress>
                                    </span>


                                </ContentTemplate>
                                <Triggers>
                                    <asp:AsyncPostBackTrigger ControlID="DDLCity1" EventName="SelectedIndexChanged" />
                                </Triggers>
                                <Triggers>
                                    <asp:AsyncPostBackTrigger ControlID="DDLArea1" EventName="SelectedIndexChanged" />
                                </Triggers>
                            </asp:UpdatePanel>

---

remove ClientMode=“Static”property

在这两个下拉列表中，AUTOPOSTBACK都是“True”。这是我的输入错误。请尝试UpdatePanel1.update（）；在下拉列表中，我尝试了它。仍然存在相同的问题。@RAJESH KUMARFirst在没有更新面板的情况下尝试是否工作正常。

<code>
 protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
        DDLCity1.DataSource = objsql.GetTable("select distinct city from tblCity where status=1 order by city");
        DDLCity1.DataTextField = "city";
        DDLCity1.DataValueField = "city";
        DDLCity1.DataBind();
        DDLCity1.Items.Insert(0, new ListItem("- All India -", "- All India -"));
        if (Request.Cookies["ddCityCookie"] != null)
        {
            ddlCity.SelectedIndex = int.Parse(Request.Cookies["ddCityCookie"].Value);

            if (Request.Cookies["ddAreaCookie"] != null)
            {
                ddlArea.SelectedIndex = int.Parse(Request.Cookies["ddAreaCookie"].Value);
            }
        }
}
protected void DDLCity_SelectedIndexChanged(object sender, EventArgs e)
{


    DropDownCityIndexChange();

    DDLArea1.SelectedIndex = 0;

}
protected void DDLArea_SelectedIndexChanged(object sender, EventArgs e)
{
    HttpCookie ddAreaCookie = new HttpCookie("ddAreaCookie");
    ddAreaCookie.Value = DDLArea1.SelectedIndex.ToString();
    ddAreaCookie.Expires = DateTime.Now.AddYears(1);
    Response.Cookies.Add(ddAreaCookie);
}
public void DropDownCityIndexChange()
{
    DDLArea1.Items.Clear();

    DDLArea1.DataSource = null;

    HttpCookie ddCityCookie = new HttpCookie("ddCityCookie");
    ddCityCookie.Value = DDLCity1.SelectedIndex.ToString();
    ddCityCookie.Expires = DateTime.Now.AddYears(1);
    Response.Cookies.Add(ddCityCookie);


    DataSet ds = new DataSet();

    if (DDLCity1.SelectedItem.Text != "- All India -")
    {
        DataTable dt = new DataTable();
        dt = objsql.GetTable("select area from tblCity where city='" + DDLCity1.SelectedItem.Text + "' and status=1 order by area");
        if (dt.Rows[0]["area"].ToString() != null && dt.Rows[0]["area"].ToString() != "")
        {
            DDLArea1.DataSource = dt;
            DDLArea1.DataTextField = "area";
            DDLArea1.DataValueField = "area";
            DDLArea1.DataBind();
        }


    }

    DDLArea1.Items.Insert(0, new ListItem("- Anywhere -", "- Anywhere -"));

}
</code>