hi
i have :

G H
2 a 30
3 a 20
4 b 40

i inserted in cell J2 :
{=IF(COUNTIF($G$2:G2;G2)<COUNTIF($G$2:$G$100;G2);" ";SUMPRODUCT(--($G$2:$G$100=G2);($H$2:$H$100)))}

here i should get : for a = 50 (WHICH IS 30+20)
for b = 40 (FOR CELL G4)

BUT MY PROBLEM IS THAT I GET INSTEAD OF THESE NUMBERS : #NUM!

NB: COLUMN G AND COLUMN H ARE RESULTS OF FORMULAS PREVIOUSLY MADE BEFORE.
HELP