The one I have works fine, too. Got mine from BestBuy. Two-player action can be a little tight, though, with bumping elbows, etc.
I have mine mounted about 3 ft off the ground.
Based on the online reviews the Zoom gets, it definitely looks like a random quality issue with some working well and others not.
My Kinect, with Zoom does not see my 30" tall, 20 lb, 15 mo old, but then again, the instructions that came with the Kinect say you have to be so big to play.