If you think you have all the settings correct in the calendar app… double check all the auto-sync settings within Android, to ensure you have covered all the basics.
Android Settings -> Accounts & Sync
1. Ensure that Background Data is “checked”
2. Ensure that Auto-sync is “checked”
3. Click the account associated with the calendar you are attempting to sync. (e.g. Google Account)
4. Ensure that Sync Calendar is “checked”
5. Click “Sync Now”
If the sync is still not working try “Synker”, free, from the market. Once installed.
1. Click on the Synker app from the app drawer
2. Ensure Sync Notification Service is “checked”
3. Ensure Sync error notifications is “checked”
That should allow Synker to display the account that is syncing in the notifications windows and if it detects sync errors it will notify you. Unfortunately you need to purchase the Synker unlock key to get to the additional information for the error but might not be needed for a quick test.
Setup a Synker widget to just sync the calendar… if you see the “sync notification” that should at least tell you that the calendar is attempting to sync.