I got the item and exited the dungeon. How do I insert the item in to the booth so I can get my reward?

I tried to click on the item so it gets attached to my cursor and then right clicking on the booth. It only causes an orange time bar to appear in the upper left corner of my screen to appear. When the bar ends the item returns to my inventory.

Replacing the right click with a normal double clcik did not help either.

Either this is a very nasty bug (The reward is a gun wich is multiple times better than my current one) or then the game manual is way too thin.