D7000 Aperture Preview Button

Hi all,

First off, I want to preface this by saying other then this issue I seem to have gotten a perfect copy of the D7000...no hot pixels whatsoever (in video or images, V1.0 firmware), focus is spot on needing no default adjustments, etc...etc...etc...

Yesterday I went to use my aperture preview button but it wouldn't work, which I thought odd. I know I'm using the APP button instead of the FN button (which is set to the virtual horizon). Even the modelling flash doesn't fire when pressing the button using the onboard flash or my SB600. I skimmed the manual but couldn't find anything pertaining to repurposing this button...it should just work...

Thoughts on what's going on or what to try? It's annoying me to no end now...

--
"In technology I'm placing all my trust"
http://www.AdamMooz.com/Photography