If you find the census on mouseclick doesn't respond to much at all, and you get some error messages popping up about attempting to call method Hookscript, then you most likely have a conflict with another addon which wants to use mouseclicks (such as VuhDo or HandyNotes, both of which were conflicting for me).
The workaround to this is: disable the option to hook into clicks on buttons and only use the click in the game world option - that solved it for me anyway, census takes quite nicely while I'm playing the game as each loot or right-click/drag to change direction triggers it (if outside the 5ish sec delay window)
