FAGLB03 DR/CR Balances don't reflect Line Item Activity

I have a client who enters an FB60 for AP Accruals and then reverses the invoice with an FB08. I'm not sure why they are doing it this way and I will discuss it with them but what is happening is the items that are reversed are not showing up in the Debit, Credit or period balance columns. It's always been my understanding that even when you cancel a document the Dr/Cr can be seen in the total Debit/Credit. Any ideas on why these canceled invoices are not showing up on the FAGLB03 Balance Display screen?