Please can you help - I had a GX7 and I could wirelessly fire my off-camera flash (Nissin i40) by using the camera's built-in flash to optically trigger it. I sold the GX7 and bought the GX85 (or GX80 as it's called in Europe) and now I cant set it up. In the menu Flash> the >Wireless and > Wireless channel are greyed out. I have mechanical shutter and silent Off. What else could it be?