Ah that's an article right here at BYC.
Here some other good ones:
https://www.backyardchickens.com/ar...incubator-thermometers-and-hygrometers.73634/
https://www.backyardchickens.com/articles/the-beginners-guide-to-incubation.73350/...
Always good to test your hygrometers and thermometers before starting an incubation.
https://www.backyardchickens.com/articles/testing-calibrating-incubator-thermometers-and-hygrometers.73634/
Also good to candle on days 7-10-14-18 tracing air cells and and removing any 'duds'.
Did you candle at...