regarding mcsi report

hi friends

In MCSI report, we select S907 info structure in the combination of Dist channel, Divi, Sales office,Sold to party and period

I Hav given dc-10,div-10, soldtoparty-50301and period 1.9.08 to 30.9.08 then screen displays with following details

Sales Billing Qty Returns incom Return billing qty Netvalue Billing Qty

00 00 15,00000- 148- 150000- 148

so, for this customer in this month no sales but sales returns are created

now the issue is last billing qty should show 148- becoz only returns happnd in that period but it is showing as positive, but when we r downloading to excel it is cominng like below

Sales Billing Qty Returns incom Return billing qty Netvalue Billing Qty

00 00 15,00000- 148- 150000- 148-

how can we make billing qty -ve in the above screen

plz reply me