FortiOS 6.0.6 no longer supports using the
execute load-balance slot manage command to access the CLI of the other chassis in a FortiGate-6000 or 7000 HA configuration.
Instead, from the primary or master FortiGate-6000 or 7000 CLI you must use the
execute ha manage command to log into the secondary FortiGate-6000 or 7000. This command logs you into the secondary FortiGate-6000 management board or FortiGate-7000 primary FIM. From here you can use the
execute load-balance slot manage command to access the CLIs of different FPCs or FIMs and FPMs in the secondary FortiGate-6000 or 7000.