You don't say what source you are connecting that has no digital sound. If you connected a soundbar directly to that source with a coax cable and still had not sound then it seems the problem is in the source.
Check the menu of the source to see if the audio is set up correctly for HDMI.
If it is a cable box try doing a cold reboot by unplugging it for a few minutes and then plug it in again. If that doesn't help get a replacement box.