Problem in Account Schedule

Hi All, Iam facing one problem in Acccount Schedule. In the inventory variance account - The period Debit and period Credit is not showing the same value it’s different. when I go to Chart of accounts for the same account, the Netchange is showing Zero. At the same time the Period Debit and Period Credit is showing the same value as what it is showing in the Account Schedule. when I copy paste the respective entries into excel and summit up I am getting different total for the same period Debit and Credit What could be the reason for this… any idea…any guess… My understanding of 1. Period Debit is sum of Debit entries for the particular period 2. Period credit is sum of credit entries for the particular period 3. Net Change - account balance during the period In TB column setup layout there is no formula.