problem in binding childitem into menu control asp.net

DataRow[] drowpar = dt.Select("Parent_Id=" + 0);
      foreach (DataRow dr in drowpar)
      {
          MenuItem objMenuItem = new MenuItem();
          objMenuItem.Text = dr["Page_Name"].ToString();
          objMenuItem.NavigateUrl = dr["Page_Url"].ToString();
          MenuBar.Items.Add(objMenuItem);
      }
      foreach (DataRow dr in dt.Select("Parent_Id >" + 0))
      {
          MenuItem objMenuItem = new MenuItem();
          objMenuItem.Text = dr["Page_Name"].ToString();
          objMenuItem.NavigateUrl = dr["Page_Url"].ToString();
          //MenuBar.FindItem(dr["Parent_Id"].ToString()).ChildItems.Add(objMenuItem);
          MenuBar.FindItem(dr["Parent_Id"].ToString()).ChildItems.Add(objMenuItem);
          //MenuBar.Items.Add(objMenuItem);`
      }

MenuBar.FindItem(dr["Parent_Id"].ToString()).ChildItems.Add(objMenuItem);