[a/s] Water pressure valve

[JAuman2346@xxxxxxx]

I have a 1976 trailer. I can't get any water into the trailer. When I attach 
the hose to the trailer and turn on the water nothing happens. I don't get 
any water anywhere. 
I have taken out the water pressure valve and attached it directly to my 
hose. Water flows with no problem. I put the water pressure valve back in the 
trailer and again no water comes into the trailer. Anybody have a similar 
problem? Is there some secret on how to adjust the water pressure valve. This 
is no easy task on a 76 25' trailer. You have to completely take apart the 
rear bathroom to get to the pressure valve.
Anybody have an idea on how to correct this problem it would be appreciated.