That could be due to the fact that PDF doesn't seem to be a widely-used module. If you really want to use that module, then after reading the thread, I'd suggest dumping a PDF that works and compare it to one that doesn't. Perhaps the problem is that one has a different encoding for the tags or some such.

If you don't mind switching to a different module, here's one that gets the information using PDF::API2:

#!/usr/bin/perl
use strict;
use warnings;
use PDF::API2;
use Data::Dumper;

my $FName = shift // die "Missing filename!";
my $pdf = PDF::API2->open($FName) or die "Can't open PDF file $FName: 
+$!";
my %pdfinfo = $pdf->info;
print "Author is: ", $pdfinfo{Author}, "\n";
print "Title is:  ", $pdfinfo{Title}, "\n";
print "\n\nAll info tags:\n", Dumper(\%pdfinfo);
[download]

If I run it on the first handy PDF file on my desktop, I get:

Author is: Texas Instruments, Incorporated [SNAS033,D
]
Title is:  LM4873   Dual 2.1W Audio Amplifier Plus Stereo Headpho
+ne Function (Rev. D)


All info tags:
$VAR1 = {
          'ModDate' => 'D:20121201221441-06\'00\'',
          'Subject' => 'Data Sheet',
          'Creator' => 'TopLeaf 7.6.028',
          'Title' => 'LM4873   Dual 2.1W Audio Amplifier Plus Ste
+reo Headphone Function (Rev. D)',
          'Keywords' => ', SNAS033,SNAS033D',
          'CreationDate' => 'D:20121201221441-06\'00\'',
          'Producer' => 'iText 2.1.7 by 1T3XT',
          'Author' => 'Texas Instruments, Incorporated [SNAS033,D
]'
        };
[download]

...roboticus

When your only tool is a hammer, all problems look like your thumb.