Set Analysis - YTD For Prior Year

[Qlik_UserEM]

Hello,

I am trying to created a dynamic YTD sales calculation through the prior full month based on a Year-Month selection.

I am able to do this for all months except January. If I select January, I would like it to show the entire prior full year.

I have this formula, but when January is selected, it just shows 0

SUM({<Year={'$(vPriorYear)'},%DATE_KEY={"<=Date(MonthStart(Min([%DATE_KEY]))-1)"},Month=,[Year-Month]=>}Sales)

%DATE_KEY = sales order date

vPriorYear = 2020

What am I doing wrong here?