Gah. You are totally correct.
For some reason I was interpreting the "bottom view" diagram as a top view. I don't know why. I read the caption each time I looked at it. With the same configuration as in my picture but the sensor flipped around everything is working fine (same as in the parasitic configuration). I do have another one of these sensors, but I guess I'm lucky that I didn't fry the one I have been using so far.
Thanks to all who replied. Please forgive such a stupid mistake.
Andy