I set the REPORT_PARAMETERS_MAP in the subreport parameters section. With this I can access all parameters from the master report in the subreport, no problems in there. Now what I need to do, is to get the same datasource from the master report in the subreport. I tried setting the subreport datasource expressions as $P{REPORt_DATA_SOURCE}, but still couldn't read the field I wanted, so I tried setting the datasource in my java code, as a parameter, then I set the datasource expression as $P{mydatasource}, but still the field value in my subreport returns null. Any ideas?