Nested aggregation not allowed

[DestinedTale]

Hi, 

I have an issue with adding $(DiffDate) to the expression in load script. 

set DiffDateformula = num(DayStart(Date#(left([@9], 8), 'YYYYMMDD'))) - num(DayStart(Date#(left([@5], 8), 'YYYYMMDD')));
let DiffDate = $(DiffDateformula) + 1;

if MonthStart($(timeStampDate)) = MonthStart($(today)) then
whichDay = $(today);
else
whichDay = num(DayStart(MonthEnd($(timeStampDate))));
endif

if (max($(whichDay)- num(DayStart(Date#(left([Due Date], 8), 'YYYYMMDD') - $(DiffDate)))) < 0, 0, max($(whichDay)- num(DayStart(Date#(left([Due Date], 8), 'YYYYMMDD') - $(DiffDate)))))) as [Aging Days]

Regards,

[uacg0009]

Hi,
Could you please share a small sample data, so I can try to find the reason,
I think maybe the variable can't get the right value, but I need a sample to prove it.
Aiolos Zhao