How to increase & print serial no in report Navision 4.0

Hi All,

I entered same item 2 or 3 times in purchase order as per below image:-


now i create report with group footer to print each single item with sum of qty as per below images:-

report displaying everything fine but is showing like 3, 9, 16 instead of correct serial nos 1, 2, 3 and i also tried to increase srno at onaftergetrecord(), onpresection() & onpostsection() but all is fail, it is not showing correct

Pls help me & tell me how i can print right .