Decklink Duo 2 Problem, only two inputs seen

I recently bought the Duo 2 because the literature said "4 x bidirectional 12-bit SD/HD independently configurable as either Input or Output"

I only seem to be able to get two inputs working. If I plug in four HD-SDI feeds, only two show as connected in the Blackmagic Desktop Video Utility, can anyone point me in the right direction to make it see all four please.

TIA

Daz

Same thing here. In Media Express only two of the inputs are enabled in the device menu.