air bag valve won,t open?

[blazer2007]

I put a A.O.L. in the back,with electric selenoids {generic brands] but to air up it won,t do it, but can hear the air sol. out work.I forgot to put in a check valve for the rear.I took out the rear valves and bench tested and work fine.It seems like there is too much pressure for the valve to open.I have just a 2 selinoid for the rear,air into one valve with a tee going to the other valve for exhaust and bags.I hope someone can make sence of this,and tell me how to spell selanoid