Problem with groups in CR9

Hi. We have a VC++ 6.0 application that uses Crystal Reports 8.5 with RDC and ReportCreationAPI. We're trying to update it to Crystal Reports 9.

Some of our reports use groups and formulas calculating the Sum of some field in a group.

The dynamic data of the report is passed with formulas (for small fields) and CDO (based on ttx files, for detail fields)

When the datasource used for grouping in a report has no records it works good in CR8.5, it just leaves all this fields and sums blank. With Crystal Reports 9 it thows exceptions "This group section cannot be printed because its condition field is nonexistent or invalid. Format the section to choose another condition field" or "this field name is not known" (if there are sum formulas on this fields).

Any solution?

Thanks