Go to the files on the PC.. check properties of the files.. if Artist, Album, and Title are missing, then the MP3 player cannot 'see' it as an MP3 player.. make sure that your media player can link to the internet to harvest track data, and add it to the tracks (there are a number of options in the media player that need to be confirmed as checked), then process all the files so that it fills the details in for you.. then upload and overwrite
Julian Pearson, February 2008