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

I am using full set of Luxman gears, D08 sacd player,c800f pre, m800a pow. When the 3 gears are on with music flow, and I touch the phase detector of rhe pre, it lights up. However, if i touch the phase detector of cdp or pow, it does not light up. I check the polarity of all the power cords and sockets, and they are all correct.

On the other hand , if i turn off either cdp or powamp, and then touch the phase detector of the pre, it does not light up.

Is the pre got problem?? My friend lent me other 800 pre to test, it won't light up.