Adding a total DR/CR column to a journal detail report

Summary

I'm trying to add a total column to report that shows journal line detail.

Content

Our implementation of oracle financials has separate fields for debit and credit entries. We are trying to determine if it is possible to total up these fields in sql to add a `total dr/cr` column.

So far I have tried to show the difference of these two fields as a separate field in sql, with and without casting them with the variable type of double. Neither pair works. As soon as I reference two fields in the syntax I don't have any values returned for this column. Does anyone know how to do this successfully?