How clean is your data?
If your are using desktop, right click that point > View Data > scroll to the fields use in calculation.
See if there is something strange about the data being used to calculate it there. That is my first guess since the calculation is working on other rows.
wow, I just found out what the problem was thanks to your suggestion. instead of 2016, it says 1016. same with the other one. Thank you for suggesting that.
It'll take a couple of those keyboard-bashing, not-knowing-what's-going-on, moments to start thinking of the "simple" solution first