Hi. I am using a second hand just bought A300 with my HVLF43AM remote flash attached to the camera. I have never set up this camera or paired it with the flash but it is attached to the shoe. I have gone to FN -> Flash mode -> Selected WL (but on the main FN menu the thunderbolt is greyed out. The camera will flash in [Auto] but the attached flash does not. What am I missing here?