DATEDIF Giving incorrect data

[PWWRB]

I have a colleague who is doing some salary work. The formula's work until the random one throws up errors and we cannot figure out why. The only fix is to insert a fresh new row into the excel and manually input the data and drag the formula down.

The formula in question is =DATEDIF(N22,dagens.dato!$A$1,"M")-P22

they are looking at previous experience plus new experience based on todays date. It works for 99% of them but random ones show up the errors. Some help would be highly appreciated.

[#2]

@PWWRB This is what MS writes about DATEDIF in their support pages:

Warning: Excel provides the DATEDIF function in order to support older workbooks from Lotus 1-2-3. The DATEDIF function may calculate incorrect results under certain scenarios. Please see the known issues section of this article for further details.

Without some example data it's difficult to tell why it sometimes goes wrong for you. Can you upload or share a file with data that include the incorrect results?