I have a basic problem on the use of Sum.

The table RPT_CERTCOL_CAR is in relation 1:n with the table RPT_CERTCOL_MIS.

There is a group on the field {RPT_CERTCOL_CAR.SEQUENZA_CAR}.

In the *header* of this group, I need to write the sum of a function:
{RPT_CERTCOL_MIS.VALORE_RILEVATO}+{RPT_CERTCOL_MIS.VALORE_RILEVATO2}

of course, referred to the rows of that group only.

I try to write a formula with this:

Sum({RPT_CERTCOL_MIS.VALORE_RILEVATO}+{RPT_CERTCOL_MIS.VALORE_RILEVATO2},{RPT_CERTCOL_CAR.SEQUENZA_CAR})

but the answer is: "The summary / running total field could not be created."

What is wrong? Thank you very much.

Using C.R. 8.5.

Thank you!