Has anyone tried this combination? I'm usually a Pocketwizard guy but thought I would experiment with using the SU800 on my Z7 to fire a SB500 off camera. I was finally able to get the flash to fire by setting the channel on the SU800 to 3 and selecing A or B on the SB500. However, 'Flash Control' on the Z7 continues to be greyed out. When I push the right arrow key on the OK selector I get the following message 'This option is not available at current settings or in the camera's current state.' Any idea what setting may be causing Flash Control to not be available?