If you cannot upload to an FTP server:
See http://www.nch.com.au/kb/10047.html for more help troubleshooting ftp connection problems.
Auto-Scan ProblemsBy default Fling uses the file's modification time and the archive flag to determine if upload is required. Most problems occur if a program or copy does not set the modified or archive flag. If this happens, right-click on the file and select Fling->Upload.