[sork] problem with forwards and qmail driver

[lanteri]

I have installed horde 2.2.4, imp 3.2.2 and forwards  ( 2.2 and
RELENG-2004-01-04)

When i try to use vacation (all version) with qmail ftp based driver
($conf['server']['driver'] = 'qmail';), I recive the following error:
Fatal error: Undefined class name 'horde_vfs' in
/srv/www/vhosts/horde/forwards-2.2/lib/Driver/qmail.php on line 194

The pear package horde_vfs in normaly installed:
# pear list 
Installed packages:
===================
Package        Version  State  
Archive_Tar    1.1      stable 
Console_Getopt 1.0      stable 
DB             1.5.0RC2 stable 
Date           1.4      stable 
HTTP           1.2.2    stable 
Horde_VFS      0.0.1    alpha
Ecc....

Anyone can help me ?
Thank you 
Domenico Lanteri