Ron, If you mean the video gain (sensors) - I'm not getting that message, and am able to set the three settings, however, if you mean the audio gain settings for mic input CH 1 and CH2, you must have the switch on the rear of the camera set to EXT (external) in order to adjust those. -s
Keystone Media Productions
It's menu control.
If one tries to change the Gain setting using the controls on LCD you can get "cannot proceed" unless you go into the "Other" menu in the camera and change Direct Menu to Part which allow you to make the change using the LCD.