crosstab header totals problem

[prosvet]

In the crosstab I have made, each cell can have positive and negative values. At the end of each row I have two columns, "Debit" and "Credit", one of which is filled according to the sign of the row total.

 

At the end of the report, I would like to put the total of the debit and credit columns. Or, the total of all positive values is not equal to the total of "Debit" column. The same is right about the "Credit" column.

 

So, is there a way to total header columns?

 

Igor