ascx文件在其他页面的单击事件之后传入数据

a页面//a页面.aspx代码
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default2.aspx.cs" Inherits="guanli_Default2" %><%@ Register src="adgroup.ascx" tagname="adgroup" tagprefix="uc1" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>无标题页</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click" />
    </div>
    <uc1:adgroup ID="adgroup1" runat="server" Visible="false" />
    </form>
</body>
</html>
a页面.cs代码
using System;public partial class guanli_Default2 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        adgroup1.AdSeriesId = "23s8d2i3";
        adgroup1.Visible = true;
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        adgroup1.AdSeriesId = "23s8d2i3";
        adgroup1.Visible = true;
    }
}

为什么Page_Load事件里adgroup控件里可以正常显示数据
而在Button1_Click事件却没有显示数据？

adgroup1的代码protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            ViewState["PageNo"] = 1;  //默认第一页
            ViewState["PageCount"] = 0;
            hfId.Value = AdSeriesId;
            Databind();
        }
    }    private string adSeriesId = String.Empty;    /// <summary>
    /// 广告系列标识
    /// </summary>
    public string AdSeriesId
    {
        get { return adSeriesId; }
        set { adSeriesId = value; }
    }    /// <summary>
    /// 显示广告组信息
    /// </summary>
    private void Databind()
    {
        BasePage.Api = "tosee.adgroup.selects";
        System.Text.StringBuilder sb = new System.Text.StringBuilder();
        if (hfId.Value.IndexOf(',') != -1)
        {
            string[] strs = hfId.Value.Split(',');
            sb.Append(" adseries in(");
            for (int i = 0; i < strs.Length; i++)
            {
                sb.Append("'");
                sb.Append(strs[i]);
                sb.Append("'");
                if (strs.Length - i != 1)
                    sb.Append(",");
            }
            sb.Append(")");
        }
        else
            sb.Append(" adseries in('" + hfId.Value + "')");
        BasePage.Parms = "pagecurrent=" + Paper + "&&pagesize=5&&out=" + PageCount + "&&where=" + sb.ToString();
        try
        {
            XmlDocument xml = BasePage.GetXml();
            XmlNode xn = xml.DocumentElement;
            if (GetFirstNodeValue(xn))
            {
                XmlNodeList xnl = xn.ChildNodes;
                ViewState["PageCount"] = xn.LastChild.Attributes["name"].Value;  //将最后一节点的值取出
                lblPageNo.Text = "第" + Paper + "页";
                lblPageCount.Text = "共" + PageCount + "页";
                XmlElement xe = (XmlElement)xn.LastChild;   //转换为XmlElement对象
                xn.RemoveChild(xe);     //从XmlNode下删除这个XmlElement节点
                xe.RemoveAll();         //删除当前节点
                repAdGroup.DataSource = xnl;
                repAdGroup.DataBind();
            }
            else
            {
                repAdGroup.DataSource = null;
                repAdGroup.DataBind();
            }
        }
        catch (Exception ex)
        {
            Response.Write(ex.Message);
        }
        DisplayLinkButton();
    }    //获取o节点下的所有节点
    protected XmlNodeList GetChildNodeList(object o)
    {
        XmlElement xe = (XmlElement)o;
        return xe.SelectNodes("AdSeries");
    }