Grand Total Problem

Hi,

I am trying to calculate grand totals in the table footer area on a single table report. The report table has a grouping with a filter. I want the grand total to sum the visible grouping data but instead it sums the entire dataset. I've tried summing the textbox but RS does not allow that from the footer. I've tried specified the group for the scope but apparently RS scope works outward not inward in regards to groups. A simple example of my problem might be a list of bank accounts whose balance is overdrawn. In the report you want to show only the accounts whose balance has gone negative and all the transactions for those accounts. You can create a group on the account field and then a filter on the group to sum the transaction amount and filter out the accounts whose sum is not below zero. The grand total would supposedly sum the accounts whose balance is negative. Unfortunately the sum is on the entire dataset and therefore includes accounts with good balances. I'm sure some will suggest changing the SQL but that is not an option for me. These seems like a very basic operation for a report writer so I'm guessing there is some easy way to do this that has eluded me. Thanks for any help.