Subreport with xlsx data source shows blank in main report

I am currently testing the jasperreport studio designer.

So what i am trying to do is to make a main report which contains a couple of subreports. Some of these subreports use an xlsx data source. When adding the subreports to the main report I use the "use a JRDatasource expression" option and enter new net.sf.jasperreports.engine.data.JRXlsDataSource(new File("path to xlsx")). But when I try to run the report I get an error message. I've noticed that the expression is for an xls datasource. But how can I change the expression so that I can use the xlsx data source?

Or isn't it possible to do this?

Thanks