Error with Subreport

[prinz reyes]

hi! im new to Jasper Report and i have a problem with subreport..and by the way im also using ireport3.0

i have my master report (Agency.jrxml) and my subreport(Employee.jrxml)..
when i run each report individually all goes well but when i add a subreport to Agency.jrxml an exception occur:

net.sf.jasperreports.engine.JRException: Could not load object from location : Employee.jasper
	at net.sf.jasperreports.engine.util.JRLoader.loadObjectFromLocation(Unknown Source)
	at net.sf.jasperreports.engine.fill.JRFillSubreport.evaluate(Unknown Source)
	at net.sf.jasperreports.engine.fill.JRFillElementContainer.evaluate(Unknown Source)
	at net.sf.jasperreports.engine.fill.JRFillBand.evaluate(Unknown Source)
	at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillColumnBand(Unknown Source)
	at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillDetail(Unknown Source)
	at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillReportStart(Unknown Source)
	at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillReport(Unknown Source)
	at net.sf.jasperreports.engine.fill.JRBaseFiller.fill(Unknown Source)
	at net.sf.jasperreports.engine.fill.JRBaseFiller.fill(Unknown Source)
	at net.sf.jasperreports.engine.fill.JRFiller.fillReport(Unknown Source)
	at net.sf.jasperreports.engine.JasperFillManager.fillReport(Unknown Source)
	at com.las.platf.cl.reports.jasper.JasperUtil.fillReport(JasperUtil.java:28)
	at com.pmbest.view.TestEmployeeReportView.generateReport(TestEmployeeReportView.java:69)
	at com.pmbest.test.reports.AgencyReportTest.main(AgencyReportTest.java:11)

this is what i did:

Map<String,JRDataSource> params = new HashMap<String, JRDataSource>();
		params.put("subDataSource", subDataSource);
JasperPrint print = JasperUtil.fillReport(REPORT, params, dataSource);

where: REPORT-->path of my master report and dataSource--> is the dataSource of my master report
i passed my subreports dataSource as a parameter to my master report..
my subreports dataSource is a list of employees.

i think the problem here is the report can't load the parameter that i passed..but how can i pass the dataSource of my subreport to fill its parameters?
can someone help me with this?
thank you...