DDJ1000 VINYL MODE bug on only deck 4

Hey,

I have a DDJ1000,

the vinyl mode works fine on all decks 3/1 and 2, but on deck 4 it doesn't work at all.

while on deck 4 when I press shift, the red light on the SLIP(VINYL) doesn't turn on.
note: The vinyl mode works just fine while on deck 2