I see a bunch of unused solder pads on the right hand side of that thing. Perhaps it needs a good 5vcc going to it? Also, are you sure it's specifically for an A500? With the way the female 86-pin port is mounted in relation to the Zorro's/etc., looks almost better suited for an A1000 or a Bodega Bay type case of some kind anyway.
-edit- Nevermind. That A1000 looking expansion case looks to be exactly what that thing was designed for. How cool! That case is totally awesome. So this was a German expansion product that essentially turned your A500 into a pseudo A1000? Incredible.
You're coming up with quite the oddities lately!