[Lilux-help] rdiff-backup

Hi If I want to do a backup of a folder (/home) an a mounted disk, rdiff-backup shows me an error message: Fatal Error: Destination directory /media/home exists, but does not look like a rdiff-backup directory. Running rdiff-backup like this could mess up what is currently in it. If you want to update or overwrite it, run rdiff-backup with the --force option. The partition is empty, only contains a lost+found folder. /media/home is a partition on an extern HD connected by USB. It has right permissions to read and write on it, it is my own: alex@kubuntu:/media/home$ ls -la total 24 drwxrw-rw- 3 alex alex 4096 2007-06-17 10:40 . drwxr-xr-x 24 alex alex 4096 2007-06-17 10:27 .. drwxrw-rw- 2 alex alex 16384 2007-06-17 00:00 lost+found The system is a kubuntu 7.04 with rdiff-backup 1.1.5. What's going wrong there? Thanx Al