My files are mp3 files. And exatly the same files from the firefly server play well with iTunes.
In Amarok forum I found this :
http://amarok.kde.org/forum/index.php/topic,13561.0.html
the “bug” seems to exist with version 1.4.4, 1.4.5 and 1.4.6.
I’m going to try with banshee, in fact found why with ssh tunnel it doesn’t see my shared library …