The listFiles() method of org.apache.commons.net.ftp.FTPClient works fine with Filezilla server on 127.0.0.1 but returns null on the r
Have you tried checking that you can list the files using normal FTP client? (For some reason, I cannot even connect to the FTP port of "belnet.be".)
EDIT
According to the javadoc for listFiles(), the parsing is done using the FTPFileEntryParser instance provided by the parser factory. You probably need to figure out which of the parsers matches the FTP server's LIST output and configure the factory accordingly.