Access is denied 0x80070005 in windows phone 8.1 when I open stream to write with taglib sharp portable

Question

there. I have a little problem with taglib sharp portable. I want to open a stream from music library and I want to rewrite properties of a file.

My code is:

StorageFolder musicFolder = KnownFolders.MusicLibrary;
StorageFile file = await musicFolder.GetFileAsync( filename );
var stream = await file.OpenStreamForWriteAsync();
File tags = File.Create( new StreamFileAbstraction( filename, stream, stream ) );

.... // modify my tags

tags.Save();

In var stream = await file.OpenStreamForWriteAsync(), I have this error:

'System.UnauthorizedAccessException' in mscorlib.ni.dll Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))

What's the problem? This code works if I want to open a stream for read only the tags. Why this code not works? If I use taglib sharp (not portable) and I do:

File tags = File.Create( filepath );

I have a problem in tags.Save() with a error

System.StackoverflowException.

What I have to do?