Birt reports, which consists of at least one scripted data source, currently cause class cast exceptions due to a cast operation (in BirtReportEngine.java, line 163).
I modified a few lines in org/efs/openreports/engine/BirtReportEngine.java to solve this problem:
replace the line
OdaDataSourceHandle dataSH = (OdaDataSourceHandle) iterator.next();
Object item = iterator.next();
if (!(item instanceof OdaDataSourceHandle)) continue;
OdaDataSourceHandle dataSH = (OdaDataSourceHandle) item;
and openreports is able to generate reports with scripted datasources as well.