Need help with hydraboost install!!

[Lex]

I need some assistance from all you hydraboost experts. I am pretty sure the power steering is good. No foam or bubbles and no leaks that I can tell. On the master cylinder side I'm pretty sure there is no leaks anywhere there either. I bled the brakes twice using the motive products tool at 15 lbs. of pressure. When the car is off the brake pedal seems like it has good pressure on it but when the car is on I lose brake pressure and it feels soft and the pedal comes up slow. Also its not really stopping the rear wheels from turning either. Please help! Thanks!