Why does the Catholic church not sanction the KJV translation?

One of my favorite Bible translations has always been the King James (I suppose because of the medieval feel), but I have always been fascinated by the much longer history of the Catholic Church and I recently was informed that the KJV is not considered a valid translation in Catholic canon. This sparked curiosity on my part I was wondering in what ways the KJV was different from a traditional Catholic translation, and can the differences be chalked up to slightly different translations of ancient Greek? Or was it fundamentally changed to fit a Protestant perspective?