Disney’s National Treasure: Book of Secrets debuted back in 2007. The sequel to 2004’s National Treasure, it reunited director Jon Turtletaub with stars Nicolas Cage, Justin Bartha, Diane Kruger and Harvey Keitel. And more importantly, it was a hit, making more than $450 million worldwide (and by August 2009 had made at least another $100 million on home video). And while Turtletaub and producer Jerry Bruckheimer would periodically tease another installment, beginning as early as 2008, one never materialized. And now we might know why we never got a third National Treasure adventure. Collider’s own editor-in-…