filling combobox with datatable

Question

Hi :) I'm trying to fill a combobox with a datatable, but i don't know what's wrong, because it doesn't display any item. This is the code:

SqlConnection conn = new SqlConnection();

            conn.ConnectionString = "Data Source=.\\SQLEXPRESS;AttachDbFilename='C:\\Users\\Vio\\Desktop\\Gestiune asigurari auto\\Gestiune asigurari auto\\Resources\\asigurari.mdf';Integrated Security=True;Connect Timeout=30;User Instance=True";

            conn.Open();

      

            string selectClient = "SELECT * FROM client WHERE UPPER(SUBSTRING(denumire, 1, 2)) = 'RO' and tip_client='altul'";

            SqlDataAdapter da = new SqlDataAdapter(selectClient, conn);

            DataTable dt = new DataTable();

            da.Fill(dt);

            for (int i = 0; i < dt.Rows.Count; i++)

            {

                comboBox1.Items.Add(dt.Rows[i]["denumire"]);

            }

            conn.Close();

the connection works fine, i've tested it.