Can't get data from database "No data exists for the row/column"

Hi here is the code I wrote. there is no error at my connection and my database is filled with data which I want to take but I cant get "Urunler.isim" datas I always get "No data exists for the row/column" error message at my sSQL2 code thanks already for your help :) .

class urunadapter
   {
       public void urungetir(string firma , ComboBox cmburun)
       {
           companymodel.cnvt conn = new companymodel.cnvt();
           conn.baglan();
           DataSet dt = new DataSet();

           string sSQL = "SELECT * FROM Firmalar WHERE Firmalar.isim='" + firma + "'";
           OleDbCommand komut = new OleDbCommand(sSQL,conn.baglanti);
           OleDbDataReader oku = komut.ExecuteReader();


           string sSQL2 = "SELECT Urunler.isim FROM Urunler WHERE Firmalar.FirmaID="+oku["FirmaID"]+"";
           komut = new OleDbCommand(sSQL2,conn.baglanti);
           OleDbDataAdapter adp = new OleDbDataAdapter(komut);
           adp.Fill(dt, "Urunler");
           cmburun.Items.Add("Seçiniz");
           cmburun.SelectedIndex = 0;
           foreach (DataRow listele in dt.Tables["Urunler"].Rows)
           {
               string satir = listele[0].ToString();
               bool durum = cmburun.Items.Contains(satir);
               if(!durum)
               {
                   cmburun.Items.Add(satir).ToString();
               }
           }
           conn.bkes();

Tags: C#