can't sftp into my second account

i can sftp into my first accoun but when I try to do it withmy second account it says The server rejected SFTP connection, but it listens for FTP connections.

What does it mean "second account"? Second user account on the same host? Or some completely different host? Can you connect to that "second account" using any other SFTP client? Aren't you supposed to use FTP protocol? (as the server seems to support it)