Inserting in to a list box. Insertions not appearing.

  TexationJobsEntities de = new TexationJobsEntities();

            var operatives = from o in de.Operatives
                             select new {o.OperativeID, o.First_Name, o.Last_Name};

            foreach (var operative in operatives)
            {
                operativesListBox.Items.Insert(operative.OperativeID, operative.First_Name + " " + operative.Last_Name);
            }

  TexationJobsEntities de = new TexationJobsEntities();

            var operatives = from o in de.Operatives
                             select new {o.OperativeID, o.First_Name, o.Last_Name};

            foreach (var operative in operatives)
            {
                operativesListBox.Items.Add(operative.First_Name + " " + operative.Last_Name);
            }