Factory Temp Gage-Retrofit=No Worky!

Recently installed a Eurosport gauge cluster of same year, motor, & trans into my "plain" '89 Celeb w/ the 'idiot' cluster, and also the factory sensor for temp. in the cyl. head; it all plugged-in, done.

What I am experiencing is: when starting, the temp gauge 'tachs out', and the reading on the gauge, in operation , never quite reaches 'normal' range, AND, the 'Temp' light glows dull red...

I know this is wrong, because I have owned (2) other Celebs,'86 & '88 Euro, w/gauge pkg. factory, all V6 mtr., and gauge needle never moved @ start, and always read accurate, no glowing temp light...

So, what am I missing here?? Please HELP~GM

Is there a good ground going to the motor?
also might want to check the wire going to the sensor, make sure its not corroded or broken

Yes, the sensor wires and plug are fine-oem gauge sensor from a working vehicle. I have visually checked the ground wires,they are in place; however, just last week the blower motor stopped running, and after fuse check, went to wires...connection was corroded. Cleaned and reconnected-works fine. DOH!  Thanks for the simple reminder! I'll physically inspect the grounds~GM