Unable to backup

Good day.

I'm using Communications Manager 7.1.1.4
Whenever I try to run a backup, it consistently fails.
If I try to download in browser, nothing happens.
When I try to set a simple FTP schedule for Sunday at midnight it pops up two warnings:

Server returned FAILURE with no error message

and

The server encountered the following errors:
Missing or invalid backup FTP server

I've checked with my local Filezilla FTP server each time and it never received any attempts to establish a connection.

I can ping the FTP server from the Thirdlane server.
My firewall accepts everything on the eth interface.

What can I do?

Thanks.