Error code: I/EX399

[J_N]

I have report with 4 subreports. It also uses external java class which retrieves data from database by report connection. When I run it from iReport, everything is OK. I also run it from small java application made in JDeveloper 10.1.3. When this line is processed

JasperPrint print = JasperFillManager.fillReport(report, parameters, connenction);

, whole application is aborted (in about 80% of cases) and dialog "Fatal Internal Error, Error code: I/EX399" is shown. I am not sure whether it is caused by Jasper or by JDeveloper. Has anybody seen this before too ?