[horde] ingo filter: unable to create vfs

[Wolfgang]

Hello,

if i "activate" the "script" in ingo, i'll alwas get the following message:
"There was an error activating the script. The driver said: Unable to
create VFS directory"

I don't know what's wrong. horde does not try to connect to the ftp and
i cannot find any entry in the horde.log.

This is my backends.php:
$backends['maildrop'] = array(
    'driver' => 'vfs',
    'preferred' => 'localhost',
    'hordeauth' => false,
    'params' => array(
        // Hostname of the VFS server
        'hostspec' => 'localhost',
        // Name of the maildrop config file to write
        'filename' => '.mailfilter',
        // The VFS username to use, defaults to current user. If you want to
        // use a different user, you also need to disable 'hordeauth' above.
        'username' => 'myvfsuser',
        // The VFS password to use, defaults to current user's password
        'password' => 'myverysupersecretpassword',
        // The path to the .mailfilter filter file, defaults to the filters'
        // owner's home directory.
        // You can use the following variables:
        //   %u = name of the filters' owner
        //   %d = domain name of the filters' owner
        //   %U = the 'username' from above
        // Example:
        //   '/data/maildrop/filters/%d/%u'
        //   This would be translated into:
        //  
'/data/maildrop/filters/<filter_owners_domainname>/<filter_owners_username>/.mailfilter'
        'vfs_path' => '/%d/.FILTER/%u@%d/',

        // VFS: FTP example
        // The VFS driver to use
        'vfstype' => 'ftp',
        // Port of the VFS server
        'port' => 21,
        // Specify permissions for uploaded files if necessary:
        // 'file_perms' => '0640',

    ),
    'script' => 'maildrop',
    'scriptparams' => array(
        // What path style does the IMAP server use ['mbox'|'maildir']?
        'path_style' => 'maildir',
        // Strip 'INBOX.' from the beginning of folder names in generated
        // scripts?
        'strip_inbox' => false,
        // An array of variables to append to every generated script.
        // Use if you need to set up specific environment variables.
        'variables' => array(
            // Example for the $PATH variable
            // 'PATH' => '/usr/bin'
        )
    ),
    'shares' => false
);


Greetings
Wolfgang