Accounting clarification pls help

Dear friends

I have one clarification in tally.

Example:Puchase 10 mobiles @ 800 each -8000Rs. & Sold 10 mobiles @ 1000 each. - 10000Rs.

via Gateway of Tally->Accounting Vouchers->F8>Sales ... updated the sale entry save it. -

I updated the delivery note- via Gateway of Tally->Accounting Vouchers>Alt+F8 mentioned the same qty 10 & without mentioned the price. Saved it.

My question is while taking stock report ,the mobile closing balance shows negative balance Purchase 10 qty Sales 10 + 10 qty 20 qty.(includes sales + delivery note qty) cl.bal -10 qty it shows. But i sold only 10 qty.

How to rectify this. Please guide me. Its very urgent

Thanks in advance

malar.d