"error unknown" message on first use

Help!

I have just set up SmartFTP v. 1.0 (from C-Net) for the first time and cannot connect.

- I have entered an FTP server address, my username and password (as required by the particular server), and I have triple-checked these, and the program recognizes the address as valid.
- The port setting is 21.
- I am using the "Normal FTP" setting.
- I have configured for 20 tries to connect to the server, and 60 secs per try.
- I have no firewall (just in case it's an issue here)

I get the following final message:

"Cannot login waiting to retry (30s)...
Continue to login attempt 21...
Connecting to (ftp. site in question) -> IP: IP in question PORT: 21
Unknown error.
Connection closed."

I have searched the Knowledge Database to no avail.

Can anyone offer advice? Please accept my thanks in advance

Catahoula