Error in the implementation of my method

public retour AnnulerPaiementWCF(ref int CodePai, ref DateTime DatePai, ref string TypePai, ref int IdPiecePai, ref decimal MontantPai, ref int IndicatPai, ref DateTime DateVersement, ref DateTime DateLimPai)
       {
           Service1 ser = new Service1();
           retour rt = new retour();


           if (ser.AnnulerPaiement(CodePai, DatePai, TypePai, IdPiecePai, MontantPai, IndicatPai, DateVersement, DateLimPai).Equals(-1))
           {
               try
               {
                   rt.CodeRetour = -1;

                   rt.msgRetour = "Annulation paiement échouée";
               }
               catch (Exception e)
               {
                   CreateLog log = new CreateLog(e);
                   log.ErrorLog(@"C:\Documents and Settings\Administrateur\Bureau\fichierLog.txt");
               }
               return rt;

           }
           else
           {
               rt.CodeRetour = 0;
               rt.msgRetour = "Annulation paiement réussite";

               return rt;
           }

       }