Autometer A/F Light show help

My son bought me a Autometer A/F gauge PN#5775 . Hooked this thing up just like the instruction sheet showed,used the red/black wire for signal,used the hot wire(key on)from the discarded clock harnes & a common ground wire. The gauge only shows 1 green light(last one on the rich side is the only 1 that lights up) drove the car for 20 miles and it still only showed that 1 green light .So I think maybe i got a bad gauge ,checked with a voltmeter and i have a fluctuating voltage on the purple wire(signal wire),so the gauge should be reading something--right?. Emailed autometer but haven't heard any response from them so thought i would ask here to see if anyone had this kind of problem before and what do you think the culprit could be.TIA

well i feel like an idiot . seems like i didn't have a good connection at the gauge. was getting my readings from the splice at the pcm,checked the connection at the gauge and that is where the problem was. THANKS for the help. Eddie