Four Wheel Drive Vacuum Lines

So my front axle has not been engaging ever since I purchased my YJ. When I shift in 4L my gear count changes in the back axle however my front axle does not engage. I pulled my vacuum actuator off of the front axle and put resistance against it and put a vacuum to it and it is functional. I replaced my vacuum lines and they are in good condition, but it still does not want to engage the front axle. So I then pulled the vacuum lines off and felt for the suction out of one hoses while in 2H, I then shifted into 4L but the suction did not change over to the opposite hose which would engage the actuator to engage the front axle. So I don't know if there is something not connected at the stick or something wrong with the suction coming from my transmission or what not, any way to test and locate the problem?

 

I can't remember exactly but I finally just only plugged one in and mine works now. They are right by the firewall on the passenger side.

 

Get one of these: http://www.quadratec.com/products/52435_0X_PG.htm

Or make it yourself: http://www.jeepforum.com/forum/f12/home-made-posi-lock-write-up-595515/