"Internally, as from SR 2 or 3, I do not know exactly any more, Poser just ignores AO settings as soon as IDL is vinked On in renders settings.
So put AO where ever you want :-)"

perhaps when used on lights, but i dont use AO on lights due to the lack of fine control. i am using a procedural shader with an AO node in PP2012 right now and it renders fine in IDL.