动态生成的repeater中的按钮无法注册ItemCommand事件

想用repeater生成无限分类,参考网上资料后决定这样做:最顶级分类使用固定的repeater控件,下属的分类都用动态生成的repeater控件,生成的分类放在一个table中,一个类别一行,带一个按钮,按钮执行删除动作.写好之后发现,分类层次可以实现无限分类要求,但是只有最顶级分类,也就是那个固定repeater控件里的按钮可以执行动作,动态生成的repeater中绑定的按钮无法执行删除动作,而且一点击,除了最顶级分类外,其他各级分类都消失了.如何处理,请大佬帮忙?
代码如下:前台html代码:<asp:Repeater ID="Repeater1" runat="server" OnItemDataBound="Repeater1_ItemDataBound" OnItemCommand="Repeater1_ItemCommand">
     <HeaderTemplate>
 <table class="tablelist">
     <thead>
     <tr>
       
        <th width="10%">编号</th>
        <th width="10%">分类树</th>
        <th width="40%">栏目名称</th>
        <th width="10%">排序值</th>
        <th width="10%">栏目类型</th>
        <th width="15%">操作</th>
        </tr>
        </thead>
        <tbody>
 </HeaderTemplate>
<ItemTemplate>          
<tr>
        <td><%# Eval("classid") %></td>
        <td><img src="images/dirfirst.gif" width="15" height="13"></td>
        <td><%# Eval("classname") %></td>
        <td><%# Eval("px") %></td>
        <td><%# getlmlx(Eval("lmlx").ToString()) %></td>
        <td>
            <asp:Button ID="btndel" runat="server" Text="删除"  CommandArgument='<%# Eval("classid") %>' CommandName="del" /></td>
        </tr>
 </ItemTemplate>   
  <FooterTemplate>
      </tbody>
    </table>
  </FooterTemplate>    
   </asp:Repeater>
后台cs代码: protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            DbUtility du = new DbUtility(cnstr, DbProviderType.OleDb);
            string str = "Select classid,classname,px,lmlx From [Class] where fatherid='0' order by px desc, classid";
            DataTable dt = du.ExecuteDataTable(str, null);
            Repeater1.DataSource = dt;
            Repeater1.DataBind();
        }
    }    protected void Repeater1_ItemCommand(object source, RepeaterCommandEventArgs e)
    {
        string id = e.CommandArgument.ToString();
        switch (e.CommandName)
        {
            case "del":
                Response.Write("<script>alert('OK1!删除成功" + id + ".');</script>");
                break;
        }
    }    protected void Repeater1_ItemDataBound(object sender, RepeaterItemEventArgs e)
    {
        if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
        {
            DataRowView drv = (DataRowView)e.Item.DataItem;
            ListInnerCategory(e.Item, drv["classid"].ToString());
        }
    }    private int currentLevel = 0;
    private void ListInnerCategory(RepeaterItem item, string ID)
    {
        string str = "Select count(*) From [Class] where fatherid=@cid ";
        DbUtility du = new DbUtility(cnstr, DbProviderType.OleDb);
        DbParameter[] pars = new DbParameter[]{
             du.CreateDbParameter("@cid",ID)
        };
        int hasc =Convert.ToInt32(du.ExecuteScalar(str, pars));
        if (hasc>0)
        {
            currentLevel++;
            string str2 = "Select classid,classname,px,lmlx From [Class] where fatherid=@cid order by px desc, classid";
            DbParameter[] pars2 = new DbParameter[]{
                du.CreateDbParameter("@cid",ID)
             };
            DataTable dt = du.ExecuteDataTable(str2, pars2);
            
            Repeater rep = new Repeater();
            CategoryTemplate template = new CategoryTemplate(currentLevel);            rep.ItemTemplate = template;
            rep.ItemDataBound += new RepeaterItemEventHandler(rep_ItemDataBound);
            rep.ItemCommand += new RepeaterCommandEventHandler(rep_ItemCommand);
            rep.DataSource = dt;
            rep.DataBind();
            item.Controls.Add(rep);
            currentLevel--;        }
    }    protected void rep_ItemDataBound(object sender, RepeaterItemEventArgs e)
    {
        if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
        {
            DataRowView drv = (DataRowView)e.Item.DataItem;
            TableRow tr = (TableRow)e.Item.FindControl("tr2");            if (tr != null)
            {
                TableCell td1 = (TableCell)e.Item.FindControl("cid");
                td1.Text = drv["classid"].ToString();
                TableCell td2 = (TableCell)e.Item.FindControl("cpic");
                td2.Text = @"<img src='images/dirsecond.gif' width='20' height='20'>";
                TableCell td3 = (TableCell)e.Item.FindControl("cmc");
                td3.Text = drv["classname"].ToString();
                TableCell td4 = (TableCell)e.Item.FindControl("cpx");
                td4.Text = drv["px"].ToString();
                TableCell td5 = (TableCell)e.Item.FindControl("clx");
                td5.Text = getlmlx(drv["lmlx"].ToString());
                TableCell td6 = (TableCell)e.Item.FindControl("cop");
                if (td6 != null)
                {
                    Button btndel = (Button)e.Item.FindControl("btndel2");
                    btndel.CommandArgument = drv["classid"].ToString();
                    
                }
                ListInnerCategory(e.Item, drv["classid"].ToString());
            }
        }
    }    protected void rep_ItemCommand(object source, RepeaterCommandEventArgs e)
    {
        string id = e.CommandArgument.ToString();
        switch (e.CommandName)
        {
            case "del2":
                Response.Write("<script>alert('OK2!删除成功"+ id +".');</script>");
                break;
        }
    }
repeater模板代码:private int currentLevel;    public CategoryTemplate(int level)
    {
        currentLevel = level;
    }    public void InstantiateIn(Control container)
    {
        TableRow tr = new TableRow();
        tr.ID = "tr2";
        TableCell td1 = new TableCell();
        td1.ID = "cid";
        tr.Controls.Add(td1);
        
        TableCell td2 = new TableCell();
        td2.ID = "cpic";
        tr.Controls.Add(td2);
        
        TableCell td3 = new TableCell();
        td3.ID = "cmc";
        td3.Attributes.Add("style", "text-indent:" + (currentLevel * 20) + "px;");
        tr.Controls.Add(td3);
        
        TableCell td4 = new TableCell();
        td4.ID = "cpx";
        tr.Controls.Add(td4);
        
        TableCell td5 = new TableCell();
        td5.ID = "clx";
        tr.Controls.Add(td5);
        
        TableCell td6 = new TableCell();
        td6.ID = "cop";
        
        Button btndel = new Button();
        btndel.ID = "btndel2";
        btndel.Text = "删除";
        btndel.CommandName = "del2";        td6.Controls.Add(btndel);
        tr.Controls.Add(td6);
        container.Controls.Add(tr);
    }