Gnomad2 is an application that enables to tranfer files (music/video) to Creative portable media players.
In Ubuntu Jaunty, if we connect the player and launch gnomad2, there is an error message :
« Aucun jukebox detecté sur le bus USB »
And therefore, it’s impossible to add media files in the player.
It is necessary to umont the player and open gnomad2, and that works fine !
Thank you to garvied for the solution.