Panel控件遍历有关问题。 获取不到子控件

           //添加代码           Panel1.Controls.Clear();            for (int i = 0; i < Convert.ToInt32(DlPerson.SelectedValue); i++)            {                Panel1.Controls.Add(new TextBox() { Text="姓名"+i.ToString(), ID="lbl"+i.ToString() });            }          //遍历代码           for (int i = 0; i < Panel1.Controls.Count; i++)            {                if (Panel1.Controls[i] is TextBox)                {                    TextBox tb = Panel1.Controls[i] as TextBox;                    guestList.Add(new Guest() { Name = tb.Text, RoomNumber = i.ToString() });                }            }