converted tiff image looks greyed out

Question

I am trying to convert bmp to tiff using the code from another thread .NET TIFF file: RGB to CMYK conversion possible without a third party library?:

    Stream imageStream = new FileStream(filename2, FileMode.Open, FileAccess.Read, FileShare.Read);
    BitmapFrame myBitmapSource = BitmapFrame.Create(imageStream);
    FormatConvertedBitmap newFormatedBitmapSource = new FormatConvertedBitmap();
    newFormatedBitmapSource.BeginInit();
    newFormatedBitmapSource.Source = myBitmapSource;
    newFormatedBitmapSource.DestinationFormat = System.Windows.Media.PixelFormats.Cmyk32;
    newFormatedBitmapSource.EndInit();

    TiffBitmapEncoder encoder = new TiffBitmapEncoder();
    encoder.Compression = TiffCompressOption.None;
    encoder.Frames.Add(BitmapFrame.Create(newFormatedBitmapSource));

    Stream cmykStream = new FileStream(filename2+".tif", FileMode.Create, FileAccess.Write, FileShare.Write);
    encoder.Save(cmykStream);
    cmykStream.Close();

I generated the original test bmp image from c#:

But my final tiff image is:

I use windows paint to see the pixal color, and the color for upper blue should be R:0 G:0 B: 255 A: 0 but it is R:24 G:74 B:124 in the tiff.

What might be wrong?