DATETIME_DIFF Formulas Help Needed! Negative Numbers

[Penny_Bell]

Why are all my DATETIME_DIFF formulas coming up as a negative number?

My formula is: DATETIME_DIFF({Birthday}, TODAY(), ‘years’) and I am getting for example -29 instead of 29.

[ScottWorld]

No, the curly braces had nothing to do with it. It was the quotation marks that were the problem.