PLD SUMCOL()

could you explain how to get the correct amount

I have 3 different fields calculated in each row one is based on quantity multiply with salesweightunit, another on salesvolumunit and the last fixed value 1

but the total is wrong it takes the total of each amount

salesvolum*qty for each line

salesweight*qty for each line....

I just want the sum when the value is shown on the report