I suspect you don't have everything enabled for searching PDF documents or the PDF you are trying to search is an image, and not a searchable PDF. The title of the PDF is file level metadata and should be searchable for pretty much any file type.
But to search the contents of a PDF, the PDF has to be searchable (ie not an image) and you have to configure Search in SharePoint to search the contents of a PDF. Taht requires more than just adding an iFilter. Take a look at the following walkthrough:
http://msmvps.com/blogs/sundar_narasiman/archive/2008/02/06/configuring-moss-2007-to-search-pdf-documents-install-and-configure-pdf-ifilters.aspx
Paul Stork SharePoint Server MVP Chief SharePoint
Architect: Sharesquared Blog:
http://dontpapanic.com/blog
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@pstork
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