PDF documents not displayed in IE9

Hi

My PDF files are not displayed in IE9 but it displays in IE8. What could be the issue. I browsed and also performed the recommended solutions like,

1. The Edit->preferences->internet->Display PDF in browser Option

2. $wa = Get-SPWebApplication = http://URLofWebApp

   $wa.AllowedInlineDownloadedMimeTypes.Add("application/pdf")

   $wa.Update()

But the issue is still the same.

Thanks.