Sql command INSERT is working but the data not appear in tha DATABASE

public void OpenConnexion()
        {
            try
            {
                 conn = new SqlConnection(@"Data Source=RAJ;Initial Catalog=GENIUS;Integrated Security=True");
                
                
                conn.Open();
            }
            catch (Exception e)
            {
                MessageBox.Show("Erreur de Connexion de la base");

            }


        }

public void InsertLP(LignePiece LP)
        {
            OpenConnexion();

            cmd = new SqlCommand("INSERT INTO F_LIGNEPIECE (EP_No,EP_Date,EP_Reference,EP_Tiers,CT_Intitule,AR_Ref,AR_Design,LP_QteMvt,LP_ValeurRemise,LP_TypeRemise,LP_TTC,LP_MontantHT,LP_MontantTTC,LP_PrixUnitaire,LP_PUTTC,LP_CodeTaxeTVA,LP_TauxTVA,N_CatCompta) VALUES" +
                                 " (,@EP_No,@EP_Date,@EP_Reference,@EP_Tiers,@CT_Intitule,@AR_Ref,@AR_Design,@LP_QteMvt,@LP_ValeurRemise,@LP_TypeRemise,@LP_TTC,@LP_MontantHT,@LP_MontantTTC,@LP_PrixUnitaire,@LP_PUTTC,@LP_CodeTaxeTVA,@LP_TauxTVA,@N_CatCompta,)", conn);
              cmd.Parameters.Add("@EP_No", LP.EP_No);
          
            cmd.Parameters.Add("@EP_Date", LP.EP_Date);
            cmd.Parameters.Add("@EP_Reference", LP.EP_Reference);
            cmd.Parameters.Add("@EP_Tiers", LP.EP_Tiers);
            cmd.Parameters.Add("@CT_Intitule", LP.CT_Intitule);
            cmd.Parameters.Add("@AR_Ref", LP.AR_Ref);
            cmd.Parameters.Add("@AR_Design", LP.AR_Design);
            cmd.Parameters.Add("@LP_QteMvt", LP.LP_QteMvt);
            cmd.Parameters.Add("@LP_ValeurRemise", LP.LP_ValeurRemise);
            cmd.Parameters.Add("@LP_TypeRemise", LP.LP_TypeRemise);
            cmd.Parameters.Add("@LP_TTC", LP.LP_TTC);
            cmd.Parameters.Add("@LP_MontantHT", LP.LP_MontantHT);
            cmd.Parameters.Add("@LP_MontantTTC", LP.LP_MontantTTC);
            cmd.Parameters.Add("@LP_PrixUnitaire", LP.LP_PrixUnitaire);
            cmd.Parameters.Add("@LP_PUTTC", LP.LP_PUTTC);
            cmd.Parameters.Add("@LP_CodeTaxeTVA", LP.LP_CodeTaxeTVA);
            cmd.Parameters.Add("@LP_TauxTVA", LP.LP_TauxTVA);
            cmd.Parameters.Add("@N_CatCompta",LP.N_CatCompta);
            cmd.ExecuteNonQuery();
            conn.Close();
        }