If([Expiration Date] - Today()<=0, 0,[Expiration Date] - Today())
The expression [Expiration Date] - Today() on the left hand side of the operator "<" is of type duration while the expression 0 on the right hand side is of type number. The operator "<" cannot be used with these types of expressions.
What I want:
Display the days until certificate is expired. If days expired is less than or equal to 0, display 0. If days expired is greater than 0, display days until expired.
i.e. expiration date of 7/15/2016 from today 7/6/2016 displays 9 days
expiration date of 6/15/2016 from today 7/6/2016 displays 0 days
(not -21 days)