Hi Gregory! Can you share a packaged workbook with us (with any non-file data sources extracted)?
Also, just FYI, you don't need to do IF...TRUE...ELSE...FALSE. You can just evaluate a Boolean statement and take its result, like this:
DATEDIFF('month',max([Commission Date]),total(max([Commission Date]))) >= 1
DATEDIFF('month',max([Commission Date]),total(max([Commission Date]))) <= 12
That'll be tough due to sensitive information. I guess the major question is, does month only extract the month number or does it include its relative year?
If you're using DATEDIFF, it compares the month values, not names. That is, April 2016 is different than April 2015 when using DATEDIFF.
OK Great! That tells me it's a data issue not a calc issue.
That should solve it.