I select "Edit Query" for the report. The "Report Query" dialog pops up. I hit the "Read fields" button, and the fields problem reports:
"Error: General problem: error executing SQL statement for: nullCheck username and password; is the DBMS active ?!"
The datasource has been set up correctly; the "Test" button on the "Connections/Datasources" dialog reports that everything is fine. The report preview runs the report and generates correct output as expected.
This feature works fine for iReport-4.7.1. It is broken in iReport-4.8.0, iReport-5.0.0