A different Temperature guage question

[Jemost 72]

I've been trying to get the factory temp guage to work with no luck. I installed a new temp sending unit and discovered the green wire was not hot.?. With a test light, I checked the back of the guage itself and it did have power. I did a search and discovered most folks have a ground problem that makes the guage peg to hot..mine is dead on cold. When I ground the back of the guage, the needle pegs hot, so I assume that should show the guage is working. Can some1 point me in the direction I need to be checking. Exactly where does the green wire go to??
T.I.A. for any info!