You seem to be on an older version of Rebex FTP component because the Ftp.Settings property was added in release 2012R1 ( no matter whether you use C# or VB.NET).
However, as written above, MLST command is used automatically since release 2012R2. You can login at www.rebex.net/protected and see what version you can actually download. If your support contract expired before 2012R2 was released (which was in June 2012), then you will need to update your support contract to be able to download the new version, which can be also done at www.rebex.net/protected page.
If you experience problem with the version 2012R2 or later, please create a log of communication as described http://www.rebex.net/kb/logging/
and then either post it here or send to email@example.com.