Flatbed Trailer no brake release and no air bag inflation

My husband has an 06 East flatbed trailer that has no brake release and no air bag inflation. He put a new air valve on, thinking this was the problem, checked the other valve, has air going to the trailer - still not working. Able to get 100 plus psi to trailer at high idle, air exhausting out of main trailer valve. Still the brakes won't release and the air bags won't inflate - any ideas what else to check for?

 

Do you know where in the system the dump valve is located?

 

Yes it is

 

it's the main service valve for the brakes

 

ok, he doesn't believe he has this valve - when he sets the trailer brakes, it automatically dumps the air out of the system