Problem with an expression in a chart object

[#1]

Hello,

I have an expression in a chart (pivot table) that uses

count(DISTINCT if(Invoice_Date <= date(aggr(max(Invoice_Date),ArtikelNr, FOKID)-14) , Invoice_Number))

It comes back with an incorrect value.

The result only works if there is only one Invoice that match the criteria OR if you select a specific invoice.

I have narrowed it down to this part

date(aggr(max(Invoice_Date),ArtikelNr, FOKID))

If I use this alone in another expression it comes back with the correct result so I know that it is working

Anyone know why this is not working properly?

br

Martin