[sork] how to enable sork-vacation?

[Thijs Koetsier | Exception]

Hello,
 
I've installed sork-vacation 2.2.2.1 on a machine running Debian 3.1 with
horde3/imp4 ( and vacation 3.3.0).
 
Can anyone explain to me how I enable Sork-vacation? It doesn't show up in
Horde or IMP, I cannot select it from the pulldown as an application to show
in IMP? The documentation in usr/share/doc only tells me to edit
/etc/sork-vacation configuration file, which I did.
 
Any help in the dark would be appreciated!
 
Kind regards,
Thijs