
Synchronization is not working correctly
The most important thing to know when troubleshooting synchronization problems is that all decisions about whether or not to transfer a file are made by comparing the file's modification dates.
A common problem is the server being in a different time zone, or just having its clock be off by more than a few minutes. The "Determine server time offset automatically" checkbox will attempt to resolve any discrepancies, but may not work on all servers. You can also try manually entering the time difference.
Another issue to be aware of is that FTP servers report only the hours and minutes of the file's modification time. Modifications occuring less than 60 seconds apart may cause unexpected syncing behavior.