LOL, you need to put check marks on the box for each tab, i.e. music, movies, photos, etc., before you click sync. If none of the boxes on "music" is checked, of course it will not sync. Also, make sure you don't have an ungodly amount of music on your iTunes or it will create a separate iPhone favorites which may not include your faves.
OK I have tried since 7 last night getting my iTunes on my iPhone ( uninstalling iTunes restalling etc.even upgrading my AOL page) OK. Go to your iTunes page. Click on music under the heading Library. Put a check mark in the boxes of the songs you want on your iPhone. Then on your iPhone information page for Music put a check mark on Sync music and sync all songs and playlist. (hint it only does the songs you checked earlier) Then click sync on the bottom. IT WORKED FOR ME! GOOD LUCK!