Synchronization does not work
From my knowledge of the Sync functionality on the Android it only syncs when it has something new on one of those services. It uses Push technology to send you the latest updates as soon as they become available.

If however new items are appearing in your mail, contacts and/or calendar and it's still not syncing then I would recommend you remove your Google account and re-add it again.

NB. I did have an issue with Sync once where it just wasn't pushing any emails to my phone... it fixed itself after a couple of days.