Show Previous Balance value in Report.

Hi,

I'm using Crystal Reports with Visual Studio 2010. I'm generating a report which shows columns Debit and Credit and SUM values on the buttom of each column. The report is filtered using a date range, which I specify in my connection via C# code (below).

            string sqlString = "";

            sqlString = "SELECT * FROM Ledger WHERE ([Payment Date] >= #" + FromDate + "#) AND ([Payment Date] <= #" + ToDate + "#)";

Now I need a "Previous Balance" value, which would be the SUM of Credit and Debit columns, which are prior to "Payment Date".  How do I accomplish this?  I've attached a sample of the report I'm looking for. Please be specific with your reply, because I'm new to Crystal Reports.

Thank you so much for your help.

Aron