Try to check PDF extracting errors:

#!/usr/bin/perl -w
use PDF::Extract;

my $pdf=newPDF::Extract(PDFPages=>"1", PDFDoc=>"/folder/form.pdf");

my $res $pdf->savePDFExtract(PDFPages=>"1", PDFDoc=>'/folder/form.pdf'
+, PDFCache=>"/folder");

print 'ERROR: '.$pdf->getVars("PDFError") unless $res;
[download]

and permissions of your dir where you tried store result.

      
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SV* sv_bless(SV* sv, HV* stash);