CsvHelper creating blank files

Question

I need create a .csv or .txt file from Collection. I'm using the library CsvHelper and I developer the following extension method:

public static class CsvWriter
    {
        public static void Write<TMapping, TModel>(this IEnumerable<TModel> items,
                                                   string fullname,
                                                   string separator,
                                                   Encoding encoding,
                                                   string culture)
            where TMapping : ClassMap, new()
        {
            var inputFileDescription = new CsvConfiguration(new CultureInfo(culture))
            {
                Delimiter = separator,
                Encoding = encoding,
                IgnoreBlankLines = true
            };


            using (var sr = new StreamWriter(fullname))
            using (var csv = new CsvHelper.CsvWriter(sr, inputFileDescription))
            {
                sr.AutoFlush = true;

                csv.Configuration.RegisterClassMap<TMapping>();
                csv.WriteRecords(items);

                csv.NextRecord();
            }
        }
    }

Above, following the class of domain, model and mappings:

 public class FuturesFiles 
    {
        public DateTime TradeDate { get; set; }
        public string BmfAccount { get; set; }
        public string Side { get; set; }
        public decimal Quantity { get; set; }
        public decimal? Strike { get; set; }
        public string Type { get; set; }
        public string Payout { get; set; }
        public decimal? Price { get; set; }
        public string Ticker { get; set; }
        public string Broker { get; set; }
        public string Counterparty { get; set; }
        public string Desk { get; set; }
        public string Exchange { get; set; }
        public DateTime ArrivalDate { get; set; }
        public string Currency { get; set; }
        public int ContractId { get; set; }
}

public class FuturesFilesModel 
    {
        public DateTime TradeDate { get; set; }
        public string BmfAccount { get; set; }
        public string Side { get; set; }
        public decimal Quantity { get; set; }
        public decimal? Strike { get; set; }
        public string Type { get; set; }
        public string Payout { get; set; }
        public decimal? Price { get; set; }
        public string Ticker { get; set; }
        public string Broker { get; set; }
        public string Counterparty { get; set; }
        public string Desk { get; set; }
        public string Exchange { get; set; }
        public DateTime ArrivalDate { get; set; }
        public string Currency { get; set; }
        public int ContractId { get; set; }

    }

public class FuturesFilesMappings : ClassMap<FuturesFilesModel>
    {
        public FuturesFilesMappings()
        {
            Map(i => i.TradeDate).Name("Trade Date").Index(1);
            Map(i => i.BmfAccount).Name("A/C Ref").Index(2);
            Map(i => i.Side).Name("B/S").Index(3);
            Map(i => i.Quantity).Name("Lots").Index(4);
            Map(i => i.Type).Name("Type").Index(5);
            Map(i => i.Payout).Name("Price").Index(6);
            Map(i => i.Price).Name("Price").Index(7);
            Map(i => i.Ticker).Name("Ric").Index(8);
            Map(i => i.Broker).Name("Exec Firm Name").Index(9);
            Map(i => i.Counterparty).Name("Contraparte").Index(10);
            Map(i => i.Desk).Name("MESA").Index(11);
            Map(i => i.Exchange).Name("Exchange").Index(12);
            Map(i => i.ArrivalDate).Name("Delivery").Index(13);
            Map(i => i.Currency).Name("Curr").Index(14);
            Map(i => i.ContractId).Name("AGE").Index(15);

        }
    }

In the repository, Ihave the functions above for call the Write funtion to writing .csv file:

public class FuturesFilesRepository
    {      

        public void WriteCsvFile(string fileName, IEnumerable<FuturesFiles> futuresFiles)
        {
            var futuresFilesModel = futuresFiles.Select(oper =>
            {
                var model = new FuturesFilesModel();
                CreateModelFutures(oper, model);

                return model;
            }).ToList();


            futuresFilesModel.Write<FuturesFilesMappings, FuturesFilesModel>(fileName, ";", System.Text.Encoding.UTF8, "pt-BR");
        }

        void CreateModelFutures(FuturesFiles oper, FuturesFilesModel model)
        {
            model.TradeDate = oper.TradeDate;
            model.Type = oper.Type;
            model.Ticker = oper.Ticker;
            model.Strike = oper.Strike;
            model.Side = oper.Side;
            model.Quantity = oper.Quantity;
            model.Price = oper.Price;
            model.Payout = oper.Payout;
            model.Exchange = oper.Exchange;
            model.Desk = oper.Desk;
            model.Currency = oper.Currency;
            model.Counterparty = oper.Counterparty;
            model.ContractId = oper.ContractId;
            model.Broker = oper.Broker;
            model.BmfAccount = oper.BmfAccount;
            model.ArrivalDate = oper.ArrivalDate;
        }

However, regardless of what I do or change, the file to be generated always comes blank. I've seen other ways to build a .csv writer, however, everything I've seen is very similar to what I'm trying to do. Could someone tell me what I'm doing wrong?