Check:
1. Your FTP server is not running, or
2. You are entering the wrong IP address or hostname in your FTP client, or
3. Your FTP server is blocked by a firewall
Ensure that your FTP server is running by logging in via SSH and running:
/etc/init.d/centovacast start-ftp
Then try connecting again. If it still fails, then the problem is either number 2 above (in which case you need to figure out the correct IP address or hostname) or number 3 above (in which case you need to ask your systems administrator to open the correct port).