动态CollapsiblePanel创建时具有相同ID错误的多个控件

Question

我正在尝试使用ajax工具包构建一个带有多个可折叠面板的动态页面。但是当页面加载时它会给我：

“找到了具有相同ID'_ClientState'的多个控件.ViewControl要求控件具有唯一ID。”

（我在阅读this article中的提示5后编写了代码）

我调试并检查了所有ID都是唯一的但仍然会发生。

我创建了一个代表候选人的类，我正在使用它从ms sql中获取所有候选人 并为每个创建一个可折叠面板，如下所示：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Collections.Specialized;
using System.Web.Security;
using System.Data.SqlClient;
using AjaxControlToolkit;


public partial class member_pages_member_page1 : System.Web.UI.Page
{
    dbservices db = new dbservices();
    protected void Page_Load(object sender, EventArgs e)
    {

        //NameValueCollection coll = Request.QueryString;
        //string s1 = coll["role"];
        string [] role=Roles.GetRolesForUser();

        if (role[0] == "secretary")
        {
            Table tbl = new Table();
            TableRow row1 = new TableRow();

            TableCell cell1 = new TableCell();
            cell1.Text = "Member name";
            TableCell cell2 = new TableCell();
            cell2.Text = "Application date";
            TableCell cell3 = new TableCell();
            cell3.Text = "Days Waiting";

            row1.Controls.Add(cell1);
            row1.Controls.Add(cell2);
            row1.Controls.Add(cell3);

            tbl.Controls.Add(row1);

            int i = 1;


            List<candidate> candidate1 = db.return_secretary_candidates();

            foreach (candidate c1 in candidate1)
            {
                DateTime today = DateTime.Today;
                TimeSpan diff = today.Subtract(c1.app_date);


                // Create Header Panel

                    Panel panelHead = new Panel();
                    panelHead.ID = "pH"+i.ToString();
                    panelHead.CssClass = "cpHeader";
                // Add Label inside header panel to display text
                    Label lblHead = new Label();
                    lblHead.ID = "lblHeader"+i.ToString();
                    panelHead.Controls.Add(lblHead);

                    member m1 = db.return_member(c1.id);
                //Create Body Panel
                    Panel panelBody = new Panel();
                    panelBody.ID = "pB"+i.ToString();
                    panelBody.CssClass = "cpBody";
                // Add Label inside body Panel to display text
                    Table table1 = new Table();
                    table1.ID = "details_tbl"+i.ToString();

                    TableRow r1 = new TableRow();
                    TableRow r2 = new TableRow();

                    TableCell cell11 = new TableCell();
                    TableCell cell12 = new TableCell();
                    TableCell cell13 = new TableCell();
                    TableCell cell14 = new TableCell();

                    cell14.Text = m1.f_name + " " + m1.l_name;
                    cell13.Text = m1.prof.secondary;
                    cell12.Text = m1.experience.ToString();

                    cell11.Text = m1.exp_brief;

                    r1.Controls.Add(cell11);
                    r1.Controls.Add(cell12);
                    r1.Controls.Add(cell13);
                    r1.Controls.Add(cell14);

                    r2.Controls.Add(cell11);

                    table1.Controls.Add(r1);
                    table1.Controls.Add(r2);

                    panelBody.Controls.Add(table1);



                // Create CollapsiblePanelExtender
                    CollapsiblePanelExtender cpe =new CollapsiblePanelExtender();
                    cpe.TargetControlID = panelBody.ID;
                    cpe.ExpandControlID = panelHead.ID;
                    cpe.CollapseControlID = panelHead.ID;
                    cpe.ScrollContents = false;
                    cpe.Collapsed = true;
                    cpe.ExpandDirection =
                    CollapsiblePanelExpandDirection.Vertical;
                    cpe.SuppressPostBack = true;
                    cpe.TextLabelID = lblHead.ID;
                    cpe.CollapsedText = c1.name + " " + c1.app_date.ToString().Substring(0, 10) + " " + Convert.ToString(diff.Days);
                    cpe.ExpandedText = c1.name + " " + c1.app_date.ToString().Substring(0, 10) + " " + Convert.ToString(diff.Days);

                    PlaceHolder1.Controls.Add(panelHead);
                    PlaceHolder1.Controls.Add(panelBody);
                    PlaceHolder1.Controls.Add(cpe);

                    i++;

            }


            TblHolder.Controls.Add(tbl);





        }





    }


}