The controller should be connected into the Lower-Back Port.
The Upper-Back port should be for the HDD.
Try connecting it there and then let us know if the HID Test worked.
Tried both back ports and nothing I'm afraid. Tried with a wavebird and a set of trusty DK Bongos (my daughter seems to have hidden my GC controller today!!!). The adapter also has two ports and I tried both of them individually and at the same time...
Here is the screencap












