Hi Rolf
Subreports should not be an issue. I typically troubleshoot the issue by taking out the subreport and testing it as a report of its own. Pass the dataset to it - if I get a problem, I go to the wiki Troubleshooting Issues with VS .NET Datasets and Crystal Reports - Business Intelligence (BusinessObjects) - SCN Wiki
If it does work, then I use the wiki on the whole report - subreports included as we may be looking at some linking issue.
- Ludek