Sun Report Builder - Column Calculations irregular

[Joshua]

sum(columnA - columnB) gives wrong result when column amounts are over 1 000.00. I have tried all available formatting and also created my own without success. Refer attachment

[eremmel]

When I replace values in column 'Variance' by formula '=<B1>-<C1>' the right result are shown.
I think it is important that you not only post the 'prove' of your issue, but also a representation document. A Base document with your report and some test data that shows the same inconsistency. That will make it more easy for other to analyze your reported issue.