No audio via DisplayPort to HDMI through Intensity Shuttle

Hi, I am using a BlackMagic Intensity Shuttle USB to connect an HP laptop to another computer (tried my ThinkPad and Macbook) via DisplayPort out to HDMI in on the shuttle. I have updated BlackMagic Media Express to v10 on both machines. Neither gives any audio. I get picture fine, but no sound. I've changed every preference I can think of, restarted multiple times, confirmed I can hear out of the original device, but ... no sound. Can anyone help? Thanks.

Have you plugged the HDMI end into a TV and verified that you are sending audio to the right Displayport output on the Source?

Yes I get audio from displayport direct to TV, but not from displayport/blackmagic to another PC. I've tried the sound options on the receiving pc without success.