Why do I have no brakes *Update*

[Danny2009]

I've recently fitted gti6 brakes and the fluid looked like engine oil it was so black so put fresh in

All been good up to tonight

Had 2 mates in the car one in the front one in the back

Going over wood head/snakes pass brakes was ok

Been to pick a axle up put that in the back get down the road I have no brakes

Foot goes to the floor and not actually slowing down

When going over dips in the road can feel the car like brake on its own like there is someone pulling the hand break a little

Also feels like rear brakes are binding/on

Dropped my mate and the axle off so there's me and a front seat passanger now there fine

When it happened the first time when I made the thread I had a set of wheels and a load of other shite in the car

So it only happens when I have weight in it seems

Load sensor valve f*cked?