Connect Airlens to Berkeley Audio Alpha Dac

Testing a Berkely Audio Alpha DAC that was loaned to me by a friend. The DST sounds amazIng through it connected with AES/EBU cable. I am trying to hear the Airlens and tried using a digital coax cable with a BNC adapter for the DAC side and the DAC does not recognize the connection. Anyone have an idea what I am doing wrong? Thanks in advance.