RDLC C# 2005 multiple datasets in one Table ReportItem

Question

Good day

I have created two reports one that shows debits (which works 100%), and one that shows debits against credits per day. It shows total debits and total credits per day, ie one line per day. In the SQL database I have a table for debits and another for credits. There are also various rates on each table. Debits and Credits can be bought and sold on a regular basis. In the reports we reflect the weighted averages of the days transactions 
SUM(rate * (bought - sold) / SUM(bought - sold)).

In the Debits report, I use the Debits dataset with the individual transactions as they appear in the DB. This approach works 100%. In the DebitsCredits report, I have created a View that combines the values from the two tables. Forcing me to join them per day (ie. getting totals per day, I lose the individual records). This approach gives me different results to the Debits report, wrong results, due to the fact that individual transactions "have beeen lost".

I thought of making use of the two individual tables, but cannot assign both datasets to the same RDLC table ReportItem. I also need to perform calculations between the two datasets (ie. creditamount - debitamount = balance).

Which other way can I bring the individual records of both table into the report and perform calculatins between them?

Many thanx.