As with any engine, if you get an "FTP Information incorrect message", you will want to check your FTP username and password for accuracy. Also ensure there are no extra spaces before or after any of these credentials.
If you are on a Yahoo! Merchant Solutions store platform (or Yahoo! legacy store), it's very likely that your Yahoo! Product Submit account was not set up with FTP capability. If you are on a Yahoo store platform and are getting the "FTP Information Incorrect" message, you can almost guarantee that this is the problem. But you can fix it! Here's how. Simply contact Yahoo Merchant Solutions to set up a new Yahoo Product Submit account. In some cases they may even be able to salvage your old account. Their email address is email@example.com, and their phone number is (866) 924-6676.