Odd as it may seem, when we program dual acting solenoids, we actually program them as two single acting solenoids and simply pair them together (think identical twins). We got the idea after having pnuematic trouble and turning to team 358's website for help. Below it the link. I would scroll down to "Double Solenoid Example" and "Double Solenoid Example - alternative implementation ". We've used the alternate style for years. The website also has a description of the mechanical pnematics set-up (along with almost everything else you could want to know about a robot) if you need to check your hardware.
http://team358.org/files/programming...2009-/LabVIEW/