song don't show on device

I’ve moved 75 or more songs to my Clip. The songs don’t show up on the device. When I plug the Clip into my computer the songs show that they are on the device.     Memory shows it is being used on the device…so the songs are there…just can’t find them.  Any idea whats wrong?

By any chance, are they protected (DRM) files?  If so, are you in MTP mode and do you have at least Windows XP SP2 and WMP10 (the requirements for MTP mode, which is needed for DRM files)?

Also, are the songs correctly tagged?  The Clip uses the tag information, not the filenames.