[DaveL]

Are you powering the working part of the system with over 30 psi?
Some valves need this to work.

Are you giving the valves the correct voltage?
There are 12v and 24v valves.

Are you sending pressure to one or both sides of the cylinder?
Try testing with tubing connected to both extend and retract sides of the cylinder.

Install manual dump valves and use these to verify that air is getting to the valve ports.

There is an input and an output side to most valves. Find the valve part number and look up the part to verify.

You can always call that valve's distributor, for info about the valve.
Dave