The trick with those 3D charts to to aim your focus point beyond (behind) the picture. Some folks have a hard time trying to focus at a place that is blocked and is the trick of divergig the eyes like the "blip" page.
Here is another trick you can do to see the 3d: put a clear glass over the picture, now focus on the reflection of yourself that you see on the glass, then become aware of what pops out of the 3d picture in in peripheral vision.
Focusing on your reflection on that clear glass is the same as focusing "behind" the picture. Hope that helps :-)
