Vista - writing exif data

I am resizing a jpeg file and want to add some exif data.
But the data is not written. If I use windows explorer there is nothing in
the properties and if I read again via WPF there is nothing. If I set
properties with windows explorer I can read them with WPF.
Is there anything wrong with the code? How do I write exif data correctly?



BitmapImage biPreview = new BitmapImage();
biPreview.BeginInit();
biPreview.UriSource = new Uri(local0, UriKind.Absolute);
biPreview.DecodePixelHeight = h;
biPreview.DecodePixelWidth = w;
biPreview.EndInit();
BitmapMetadata bmmd = new BitmapMetadata("jpg");
bmmd.Title = title;

BitmapFrame bmFrame = BitmapFrame.Create(biPreview, null, bmmd, new
System.Collections.ObjectModel.ReadOnlyCollection<ColorContext>( col));
bmFrame = BitmapFrame.Create(biPreview);


JpegBitmapEncoder enc = new JpegBitmapEncoder();
enc.QualityLevel = 70;
enc.Frames.Add(bmFrame);
//write to filestream
enc.Save(fs);
fs.Close();

> BitmapMetadata bmmd = new BitmapMetadata("jpg");
> bmmd.Title = title;
>
> BitmapFrame bmFrame = BitmapFrame.Create(biPreview, null, bmmd, new
> System.Collections.ObjectModel.ReadOnlyCollection<ColorContext>( col));
> bmFrame = BitmapFrame.Create(biPreview);

This code is off course unbelievable stupid... the last line will discard
the metadata.
But if I get rid off this line I get a COMException (0xc0000005) on
enc.Save(fs);
If I use
bmmd.SetQuery("/app1/ifd/{uint=270}", title);
bmmd.SetQuery("/app1/ifd/exif/{uint=37510}", title);
and do not use
bmmd.Title = title;
the metadata gets saved (although not visible for Windows explorer, but I
can do without that).