The ftp server is running on a Windows CE system (UNICODE !).
There are directory names like \Storage Card or \Application Date on this system.
When I use FTP these names are displayed correctly, when I use SSH/SFTP these directories are displayed as Card resp Data. To go into these directories I have to use DirectoryCommands/ChangeDirectory.
This is a problem of coreftp not of the ftp server because WinSCP displays the directory names correctly.