Check Brake Lights???

[LSV84U2NV]

on my computer on the dash it says check brake lights
now i have replaced both bulbs in the trunk that does the brakes and i checked the fuse in the passenger side and everything is good.
now in the trunk on the left hand side there is a grey plug in, that is not plugged into anything does this have to do with it. but if u look at the trunk roof wiring all the wiring comes down the right hand side down the lid brace.
i'm really lost here
p.s my middle brake light in the backwindshield works

 

[V-8]

i keep getting a 'right rear brake light'

checked it, works fine......weid.