Is the subreport using the same connection as the main report?
In the CMC, look at the Database Configuration for the report. Make sure that all of the connections have been set up correctly - if you’ve used a different connection for the subreport, there will be multiple connection names in the top left of the screen.
If that doesn’t work, edit your report and Set Datasource Location to make sure the main and the subreports are using the same connection then republish.
You don’t mention which version of Crystal you’re using or which version of BO or CRS you’re using. Make sure you have the latest service packs/fix packs for both.
I am actually having a similar issue, we are using CR2010. Freehand SQL being used in both the Main & subreport.
The subreports don’t seem to be picking the the DB connection, I verified in CMC DB configuration to see that they are both identical (main report & subreport).
Also, they are pointing to the same Data source.
What could be the issue here? Any help would be appreciated.