1. Please let us know what version of SyncMate you use.
2. Check again the settings. Check whether the right calendar is selected to sync with.
3. Another probable reason of the problem is Sync Service failure.
Please reset the SyncServices folder with these steps in Mac OS X 10.5:
Choose Preferences from the iSync menu.
Click Reset Sync History.
If this does not resolve your issue, or if you are unable to open iSync, follow these steps:
In the Finder, choose Utilities from the Go menu.
In the Terminal window that opens, type or paste the following command on a single line:
When the operation is complete, quit Terminal."
Let us know of the results whatever they are (please answer in this topic)