FileHelperEngine does not work with ClassBuilder

[Tabgyn]

This condition is always false when I use FileHelperEngine with ClassBuilder

FileHelperEngine.cs (line 419)

    if (RecordInfo.RecordType.IsInstanceOfType(rec) == false) {
        throw new BadUsageException("This engine works with record of type " +
        RecordInfo.RecordType.Name + " and you use records of type " +
        rec.GetType().Name);
    }

I ran the following test ...

[Test]
        public void WriteFileFixed()
        {
            var cb = new FixedLengthClassBuilder("SampleType");

            cb.AddField("Field1", 8, typeof(DateTime));
            cb.LastField.Converter.Kind = ConverterKind.Date;
            cb.LastField.Converter.Arg1 = "ddMMyyyy";
            cb.LastField.FieldNullValue = DateTime.Now;

            cb.AddField("Field2", 3, typeof(string));
            cb.LastField.AlignMode = AlignMode.Right;
            cb.LastField.AlignChar = ' ';

            cb.AddField("Field3", 3, typeof(int));

            cb.LastField.AlignMode = AlignMode.Right;
            cb.LastField.AlignChar = '0';
            cb.LastField.TrimMode = TrimMode.Both;
            
            mEngine = new FileHelperEngine(cb.CreateRecordClass());

            var records = new List<SampleType>
            {
                new SampleType {
                    Field1 = new DateTime(2010, 3, 2),
                    Field2 = "field2.1",
                    Field3 = 1
                },
                new SampleType {
                    Field1 = new DateTime(2010, 4, 5),
                    Field2 = "field2.2",
                    Field3 = 2
                },
                new SampleType {
                    Field1 = new DateTime(2010, 6, 7),
                    Field2 = "field2.3",
                    Field3 = 3
                }
            };

            mEngine.WriteFile(FileTest.Good.Test1.Path, records);

            mEngine.ReadFile(FileTest.Good.Test1.Path);
            
            Assert.AreEqual("SampleType", mEngine.RecordType.Name);
            Assert.AreEqual(3, mEngine.RecordType.GetFields().Length);
            Assert.AreEqual("Field1", mEngine.RecordType.GetFields()[0].Name);
        }

...and the following exception occurred

WriteFileFixed [0:00.256] Failed: FileHelpers.BadUsageException : This engine works with record of type SampleType and you use records of type SampleType

Would anyone have a working example of building the layout dynamically, without being the test sample here from the repository?