Lead formula not allowed for formula summary
I have a line item in percentage (POC). I already created the formula and set the summary totals to formula to get the correct %. But I need the value of the percentage for the following year. for example my period is Jan 2020, I need to reflect the value of the percentage in Jan 2021 in my Jan 2020 period. I tried using the formula LEAD to get the value. Formula : Lead(lineitem,12,0) but it is not working if the summary total is set to formula. If I dont set the summary to Formula, I will get incorrect percentage at the totals level since it will just sum it up.
How do I get now the correct value of percentage?