.rdlc Report - Cannot create a data reader for dataset 'DataSet1'

I have created a .rdlc-Report under VS 2012 using the report wizard and added data source and dataset. When I try to render the report using the code below I get following error message:

Cannot create a data reader for dataset 'DataSet1'.

bytes = localReport.Render("PDF", sdeviceinfo, out smimetype, out sencoding, out sfilenameextension, out streamids, out myWarnings);