You probably have to update the database in Crystal Reports. There may be a field that has been added and your report points to old data.
Open the report in Crystal reports.
Providing your connection hasn't changed, click the 'Database' menu item then 'Verify database'. Resave.
Please note that most reports are not modifiable in the accpac folders. Copy it to another location. Rename the report in the accpac folder to something similar to 'xxx-ORIGINAL.rpt'. This way if something goes wrong, you still have the original report. Make the changes to the report and replace it back into the accpac folder.
If at first you don't succeed, then sky diving wasn't meant for you!