Issues uploading to an anonymous FTP server.

I seem to be connecting to it successfully, but can’t upload any files to it. When I connect to it, the status message in my ftp client says “Retrieving list of files” as usual, but no list displays and after c. 5 mins, the status message changes to “Status: idle.” I see no files listed in the remote directory and I can’t upload my own files into it.

I know there’s no problem with my ftp client or my internet connection (I can upload fine, as usual, to servers other than this one). The instructions, which I’m following, say to put nothing in the username or password fields. (I tested by putting something random in the username and password fields, and doing that immediately returned the error message “login incorrect” rather than “Retrieving list of files,” so I think I can assume it’s accepting my login attempt when I put nothing in those fields.)

How else should I be troubleshooting?