try running direct 12V to the bad injector...ground out one side and hook the other to your battery. see if it clicks, do that a few time. On random occasions the injector can freeze and the extra power will cause it to unfreeze. you'll be able to hear and feel it click open and closed.
Another thing, try running a noid light on the injector harness, see if it flashes, if not run an ohm meter from the injector harness to the injector pin on your ecu, if you show nothing you've got a bad wire in there.