TDS NOT DEDUCTED ON FULL AMOUNT

We have ongoing issue of TDS on deducted on partial amount, we come to know that whenever in the voucher match application we delete any line after calling the receipt details on screen, system is not calculating the TDS for the Last Line of Voucher for example…..

Receipt Detail-F43121

Part A -QTY 1 -$ 100

Part B-QTY-2-$ 200

Total               $ 300

Now we need to voucher only Part A -QTY -2 -$ 100, but we call both the line i.e. Part A &  Part B by mistake we apply both for voucher, but as we need to account only Part A-2-QTY $ 100 we delete the second line & adding taxation line below, here system not calculating the TDS for the Taxation line.