I don't know much of anything about that model specifically, but my Sony auto-focus requires me to slightly press down on the button in order for the auto focus to actually work. When I do that I see the little... lines on the view screen, and they're all white. Once the auto focusing is done those lines turn green. At that point I can take my picture, and presto chango! they are in focus and viewable.
The Life of the Knife is Ended By! The Wife.