2000 International 9400 I Foot Valve Replaced. Now we have low air coming out of fire wall.

2000 International 9400 I Foot Valve Replaced. Now we have low air coming out of fire wall and Low air coming out emergency brake line. The emergency brake line is not push in it have low air coming out. We add air to the system I get a blow off. It not slowing any reading on the dash. the reason it was replace because it use to stick some times. This is a Bendix 800599 / E-8p / 3519692C92. He put hose back the whay it came off.