Need help on 95 set up as HDMI transport

Hi all,
I currently have NAD M51 DAC and hook up to Oppo 95 as HDMI transport. The M51 lock in when Oppo play RBCD but unlock when play SACD. I also have hi-rez files play from external HD, and still cannot lock in the HDMI signal.
I set up Oppo based on instruction from the manual (page 61)
HDMI Audio set as Auto, LPCM, Bitstream - the DAC still not lock in
SACD Output also set as PCM did not help on play SACD

If you successfully set up Oppo 95/93 as HDMI digital output to your DAC, please post your set up here
Thanks for your help
Best regards
Thuan