#!/usr/bin/perl -w
use strict;
use WWW::Mechanize;
my $agent = WWW::Mechanize->new();
$agent->get("http://europa.eu.int/prelex/rech_avancee.cfm?CL=en");
die "Can't even get the home page: ", $agent->response->status_line un
+less $agent->success;
$agent->form(2); 
$agent->field("clef2", "1999");
$agent->field("clef1", 'COM');
$agent->field("nbr_element", '99');
$agent->click();
my $input=$agent->content();
my @links = grep { $_->uri =~ m!liste_resultats! } $agent->links;
foreach my $link (@links) {
  print "Retrieving $link\n";
  $agent->follow( $link );
  print $agent->content;
  $agent->back;
};
[download]

And a very appropriate response it is, seeing as how WWW::Mechanize::Link has methods named url and URI, but none named uri.

WWW::Mechanize::Link pod

Why do you think installation of WWW::Mechanize failed? The error you encounter is a runtime error at line 13 of your script. That implies that all the calls to that module above it, have actually succeeded — or at least, not made the module barf. Heck, even the $agent->links call, on the right of your grep block, must have returned some values or you wouldn't have gotten this far.

And ikegami pinpointed the cause of your problem. A non-existing method name, that's a runtime error, as methods can even be created (by AUTOLOAD) on the fly.

Conclusion: unless the exact same script works on another computer, and I sincerely doubt that, the module most likely will have been properly installed.