MyBook Duo 12Tb and a Annke DM310 CCTV Dvr

I have a new MyBook Duo 12Tb that I have tried to use as a backup video drive on an Annke model DM310.

  1. Plugged in drive via USB port on DVR and the DVR did not recognize the drive. Tried both USB ports and neither worked.
    2)Partitioned/formatted drive using exFat on computer and reported the drive was 10.9Tb-acceptable… Plugged in drive via USB port on DVR. DVR did recognize the drive BUT reported that it was only 2.91Tb in size…
    I am scratching my head… any ideas?? Thanks!