[clearcarbon]

"If the valves work, check the drive circuitry and wiring. When commanded, does the signal get there at the proper voltage and with enough current to actuate the valve?

Wired backwards.

[Openurmind]

Bad ground...

[ThunderSleeps]

Always a possibility... Says the programmer that once turned a very expensive relay bank into a doorbell buzzer, burning through a fair portion of the hardware cycle life in a few moments....