iTunes v iPod

You should be using iTunes (or Finder on newer Mac OS) to copy the music to the iPod

• Is the music in your iTunes Library? Do the songs play in your Library?
• What settings are being used to add music to the iPod? Is it Sync Entire Library, or Sync selected playlists, artists, albums and genres? If it's the latter, the songs need to be in one of the selected lists
• Or are you using Manually Manage to drag music to your iPod? Note that if you are using one of thew Sync options, you cannot drag music to the iPod