You have installed Photopost Pro 6.23 to your forum
I do not see where you have actually turned on the enhanced integration under admin edit integration in your photopost admin panel
Freizeit Fotoknipser - Photo Gallery - Login
It really is just a matter of correctly installing. Do you speak any english?
Basically you need to login as admin and under edit integration fill out all the proper information asked about vbulletin there and then you can turn on the 3 vb3 enhanced integration switches.
Also under forum settings you turn yes the switch to use the forum style
This all was normally done on install so you must have not completed the last step