problems sending money when the wallet has more than 1 transaction

sendBtc.cs

        public bool EnviarTodo(string llavePrivada, string destino, string mensaje)
        {
            Key privateKey = Key.Parse(llavePrivada);
            BitcoinSecret bitcoinPrivateKey = new BitcoinSecret(llavePrivada);
            BitcoinAddress address = bitcoinPrivateKey.GetAddress(ScriptPubKeyType.Legacy);

            QBitNinjaClient client = new QBitNinjaClient(Network.Main);
            uint256 transactionId = uint256.Parse("42119368712db98a8fb75763fd9158848dc37ff5b180413e30a5063113b4aaa1");
            GetTransactionResponse transactionResponse = client.GetTransaction(transactionId).Result;
            
            // Creamos el objeto Transaction
            Transaction transaction = Transaction.Create(Network.Main);

            List<ICoin> receivedCoins = transactionResponse.ReceivedCoins;
            OutPoint outPointToSpend = null;
            foreach (var coin in receivedCoins)
            {
                if (coin.TxOut.ScriptPubKey == privateKey.ScriptPubKey)
                {
                    outPointToSpend = coin.Outpoint;
                }
            }

            // Validamos si existe algun ScriptPubKey
            if (outPointToSpend == null)
            {
                throw new Exception("TxOut doesn't contain our ScriptPubKey");
            }

            // Creamos la entrada
            TxIn tEtrada = new TxIn();
            tEtrada.PrevOut = outPointToSpend;
            transaction.Inputs.Add(tEtrada);

            // Salida principal
            TxOut tSalidaPrincipal = new TxOut();
            tSalidaPrincipal.Value = new Money(0.00060035m, MoneyUnit.BTC);
            tSalidaPrincipal.ScriptPubKey = new BitcoinPubKeyAddress(destino).ScriptPubKey;

            // Añadimos la salida principal a la transacción
            transaction.Outputs.Add(tSalidaPrincipal);

            // Mensaje
            if (!Cadena.Vacia(mensaje))
            {
                TxOut tMensaje = new TxOut();
                tMensaje.Value = Money.Zero;
                tMensaje.ScriptPubKey = TxNullDataTemplate.Instance.GenerateScriptPubKey(Encoding.UTF8.GetBytes(mensaje));
                transaction.Outputs.Add(tMensaje);
            }

            transaction.Inputs[0].ScriptSig = address.ScriptPubKey;

            // Firmamos la transacción  
            transaction.Sign(bitcoinPrivateKey, receivedCoins.ToArray());

            BroadcastResponse broadcastResponse = client.Broadcast(transaction).Result;

            if (!broadcastResponse.Success)
            {
                Console.Error.WriteLine("ErrorCode: " + broadcastResponse.Error.ErrorCode);
                Console.Error.WriteLine("Error message: " + broadcastResponse.Error.Reason);
            }
            else
            {
                Console.Error.WriteLine("ErrorCode: " + broadcastResponse.Error.ErrorCode);
                Console.Error.WriteLine("Error message: " + broadcastResponse.Error.Reason);
                Console.WriteLine("Success! You can check out the hash of the transaciton in any block explorer:");
                Console.WriteLine(transaction.GetHash());
            }

            return true;
        }