[horde] missing icons

[Biermann-Roemke at t-online.de]

Hello!
I'm using horde since nearly one year and it works fine.
I found that turba no allows contact lists so I upgrade to 
horde-2.2.3, imp-3.2 and turba-1.2 (after settin up apach2 and
php-4.3.3)
I can solve all problems (mostly home-made :-) but now I'm really
desperate by a small thing which is irritating to me:
I can't enable the menu-icons
In my old config/horde.php I have: $conf['menu']['images'] = true;
In my new one I don't find this line, so I added it. -> now result.
I can't figure out, where to enable, I'm searching in the faq in the
archive on marc and
try google - find nothing ... -:(
It works, but I like icons, so please give me a hint.
Thanks
         Karsten