Delphi 2010 Export to pdf

Hi all:
i wrote code to convert Quick report to pdf. its working perfect except on issue.

//  QuickRep3.Font.Charset:=178;
//  QuickRep3.Font.Name := 'Tahoma';

  Quickrep3.prepare;
  Save_to_Pdf := (repname+'\'+Cb2.text+FormatDateTime('ddMMYYHHmm',now)+'.pdf');
  QuickRep3.ExportToFilter(TQRPDFDocumentFilter.Create(Save_to_Pdf));
  QuickRep3.Preview;  // or Print
  QuickRep3.QRPrinter.Free;
  QuickRep3.QRPrinter := nil;

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the arabic language appear like garbage like question mark (??????? ) as shown in attached image. i am tired to change the font quickrep but the issue is exist.
samir.png