What is the Error you are getting?
Consider what the data table looks like
you have 4 columns
and identifier - a release date - a promise date and a revised promise date
This will select the promise date to use
date to use = ifnull([promise_date],[revised_promise_date) if the first argument is NOT null it uses the first argument - if it is null it uses the second
THen you can use the date to use in your previous formulas
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