MCI error message 277 on some files

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C#

audio

ffmpeg

Hi there!
I download and convert a audio file from the web with ffmpeg and convert them to mp3 with "-acodec libmp3lame -ab 128k" using a selfwritten wrapper in C#. This file can be perfectly played in Winamp for example.
But now I want to play this file in my C# application with MFC and the "Error 277" is thrown. With some other music files it is working.
Do you know what the problem can be?

Thanks in advance!

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PS: Do you know other working methods of how to play Mp3's using C#? I only found the MCI-way working (sometimes :P)