pdf download dialog window not appear in browser.

I am able to generate a report in pdf form using JasperReports and Java.

The generated report is not available to be downloaded to the client side. I am generating pdf file using the code below:

public void getTaskreportPDF(Session openSession,HttpServletRequest request,HttpServletResponse response) {
        try {   
Class.forName("com.mysql.jdbc.Driver");
Connection con = (Connection) DriverManager.getConnection("jdbc:mysql://localhost/contact","root","root");
Map params = getParameters(openSession);
Date date = new Date();
String reportfileName = "report"+date.getDate()+"-"+date.getMonth()+"-"+date.getYear()+"-"+date.getTime()+".pdf";
JasperDesign jasperDesign = JRXmlLoader.load(this.getClass().getResourceAsStream("/com/gantt/report/ganttreport.jrxml"));
JasperReport jasperReport = JasperCompileManager.compileReport(jasperDesign);
JasperPrint jasperprint = JasperFillManager.fillReport(jasperReport, params,con);
JRAbstractExporter exporterPDF = new JRPdfExporter();
exporterPDF.setParameter(JRExporterParameter.JASPER_PRINT, jasperprint);
exporterPDF.setParameter(JRExporterParameter.OUTPUT_STREAM, response.getOutputStream());
response.setHeader("Content-Disposition", "inline;filename="+ reportfileName);
response.setContentType("application/pdf");
exporterPDF.exportReport();  
} catch(Exception exception) {
System.out.println("Error occured " +exception.getMessage());
}
}

My firebug net tab shows that I had got the pdf report file of 4 kb as response. But the problem is that download window not appear, so I cannot save it or view that report.

My firebug shows:
Content-Disposition inline;filename=report21-0-112-1327135412907.pdf Content-Type application/pdf

What mistake I am making which makes my download window not to appear?

Use attachment instead of inline for the Content-Disposition header.