Luxman c800f preamp, need help.........

I hv full set of Luxman , D08 SACD player, c800f preamp, m800a power amp. There is a phase detector on the back. If all 3 gears are on, when i touch the pre, the phase detector will light up, when i touch cdp and pow, they will not light up. Is it normal??

But if i turn off either cdp or powamp, when i touch the phase detector of pre, it will not light up.

Any luxman users here can give me some comment??

Thanks very much.