Web开发中Repeater控件镶嵌问题

Question

Repeater2是镶嵌在Repeater1中的，代码如下

       protected void Repeater1_ItemDataBound(object sender, RepeaterItemEventArgs e)
        {
            if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
            {
                HiddenField hf = (HiddenField)e.Item.FindControl("HiddenField1");
                Repeater rt = (Repeater)e.Item.FindControl("Repeater2");
           
                rt.ItemDataBound += new RepeaterItemEventHandler(rt_ItemDataBound);
                rt.ItemCommand += new RepeaterCommandEventHandler(rt_ItemCommand);
                rt.DataSource = MessageManage.ShowRefByMID(int.Parse(hf.Value));
                rt.DataBind();
            }
        }

 void rt_ItemCommand(object source, RepeaterCommandEventArgs e)
        {
            //throw new NotImplementedException();
            Response.Write("aaa");
        }

void rt_ItemDataBound(object sender, RepeaterItemEventArgs e)
        {
            if (e.Item.ItemType == ListItemType.AlternatingItem || e.Item.ItemType == ListItemType.Item)
            {
                Button bt6 = (Button)e.Item.FindControl("Button6");
             
                bt6.OnClientClick = "return confirm('删除该回复之后将不可恢复，确定要删除？')";

             }

为什么ItemDataBound事件中的代码可以执行，而ItemCommand事件却不能执行，求解释…