So I just received my Nikon SB-500 speed light flash today and I am using a Nikon D810. I configured my built in flash to work as a commander works great but am not able to disable the in built camera flash to fire. When I want to trigger my SB-500 off camera, my camera flash also triggers along. I think am wrong with the settings. I have the Group A with Manual M in the settings , Built in and Group B settings are set to nil then too this happens. Any help ?