Smiths guages problem

[rads42]

I have a problem with my Smith's oil and water temperature gauges that's stumping me a little so I was hoping someone here had a suggestion. Both gauges read low at only about 50 C when the car's hot. At first I thought maybe the car had a stuck t-stat or something so it was never "warming up" Even though 50 was too low even for that. Also the thermostatically controlled fan comes on pretty often and that's set to come on at 75 C so I know the car is actually up to temp which would point to a gauge or sending unit problem. So last night I took the water temperature sending unit it and put it in a pan of 95 C (210 F) water to see what would happen and it didn't react at all....needle never moved. I tried this with the key off and then with the key on, no change. Anyone have any ideas? It just seems odd that both gauges would have the same problem but now that my experiment didn't work at all I'm even more puzzled.