When connected to a UNIX server, only the "Default" option is selectable. The "FTP", "ASCII", and "Binary" options are grayed out.
The options are grayed out because this is the only way it can transfer files securely. Otherwise, if they had those options enabled, it wouldn't be secured.
From FTP SERVER SETTING window, select the "FTP/Rexec" option instead of the "Secure FTP/SSH" option.