ipod wont sync

Is it set to Manually manage music on the shuffle's Summary tab (in iTunes)?

"Syncing" music and "manually managing" music are mutually exclusive, so that is probably why nothing happens when you click the sync button (if the checkbox for Manually manage music is currently checked).

When you manually manage music, you drag songs (and other items such as audiobooks and podcasts) to your iPod to load it, "manually." You select and delete individual items from the shuffle to remove them. "Syncing" content does not apply.

When you sync music, you set up the Music tab (for the shuffle in iTunes) to automatically sync the content. A convenient way to do this is to create one or more playlists (in iTunes) of songs you want on the shuffle, and then set the Music tab to only sync to those playlists. You can update (add or remove songs) those playlists, whether the shuffle is connected or not. When you connect the shuffle, iTunes syncs any changes since the last sync automatically. You can also click the sync button to do a sync, if you make changes (to the playlists) while the shuffle is already connected.

To change to syncing, uncheck the Manually manage music checkbox and set up the Music tab. Note: When you do a sync, items that are currently on the shuffle will change to reflect the sync settings (on the Music tab). Items may be added and removed, so if there are items on the shuffle that are NOT currently in your iTunes library, those items will go away.

You need to also set up the shuffle's Music tab (in iTunes), to tell iTunes what to sync to the shuffle.

This article explains all the ways to load an iPod shuffle with music. Automatic syncing is the first way.

http://support.apple.com/kb/HT1719