Hello,
Please make sure that AR6 is licensed on your machine and that the required entry for PDF export is present in your licenses.licx file :
DataDynamics.ActiveReports.Export.Pdf.PdfExport, ActiveReports.PdfExport, Version=x.x.xxxx.x, Culture=neutral, PublicKeyToken=cc4967777c49a3ff
For further details, you may refer to the following documentation link :
http://helpcentral.componentone.com/NetHelp/ActiveReports6/topic34.html
Let us know if you face any further issues.
Regards,
Mohita