Net Document value not matching to Net Item Value.

Hi gurus

We are using version 4.6. When we create condition records, alt calculation type logic increases the value by 1/365 since we want to calculate it for 366 day.Recently impemented periodic billing plan in contracts. But after that the net document value in VBAK-NETWR is not matching with net line item value KOMP- NETWR. It comes few Rs. more than the net line item value.this was not happening earlier even though the alt. calc type formula was there.Please suggest.