"Transcoding failed. Please try another video." always!

Hi everyone,

I'm working with a 5.6 Drupal installation under Windows XP (wamp).
I wish to use this module, but each time that I try to publish a video, I obtain the message in Title after running cron.php.
I freshly installed a win32 ffmpeg and I typed the correct path in configuration page (C:\ffmpeg-latest\bin\ffmpeg.exe). Log types nothing and cron apparently works well.

What do you think about?

Many thx in advance,
Alex