The initial versions of this chip had an internal thermistor. But for some reason this was removed by the vendor. They did this without revising the chip designation. The functionality basically just vanished and all mention of it removed from the revised datasheet.
We have marked the temperature function as deprecated in our libraries. If you think you can verify you have a version with a functional thermistor, then you can probably use the temperature function. But if you are getting odd or no readings when using this function, it is likely you have the newer version of the chip with no thermistor - temperature will not work.