It actually isnt that hard. U just have to copy the fields from the main report into the subreport.
this is a step by step tutorial.
I just want a subreport element that I have in my main report to be shown in the preview.
My subreport is just another report.
As i created the subreport I told jaspersoft to use the certain report as the subreport. That one has data in it and its able to be shown in the preview for itself, but not when its in the main one.
Thanks for the help,
PS: Please dont send me that tutorial page from that idian guy xD (tried that..)