I'm not sure to understand your problem.

I create a user control with the code. There's no bugs in the adapter. For
the code in the ascx.cs this is what I have done with comments from the
article...

Where CategorieBatimentList is a generic list of CategorieBatimentInfo.

I loop in my collection and then add the objects in my dropdownlist.

protected void Page_Load(object sender, EventArgs e)
   {
       if (!IsPostBack)
       {

           CategorieBatimentList catBats =
CategoriesBatiment.GetCategoriesBatiment();
           foreach (CategorieBatimentInfo catbat in catBats)
           {
               ListItem currentItem = new
ListItem(catbat.DescriptionFrancais, catbat.CodeCategorie);
               currentItem.Attributes["OptionGroup"] =
catbat.DescriptionGroupeFrancais;
               ddlCatBatiment.Items.Add(currentItem);
           }
       }
   }