you are using Rank or Index - they are table calculations that need an underlying table - so this approach will not work -
What is the end goal? there may be other ways to get the result you want without using table calculation
end goal is to find after how many Airings from first launch Product's GMV per Airing starts declining
Don't know what that means - if you attach a twbx workbook with at least some dummy data I can be more specific - but it sounds like you could use an lod to determine the date when the gmv per airing is MAX - then countd the dates that are less than the max date
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