LWP post, Cannot get result page

I have been trying to learn LWP Post, by going through an examples on the web. Perl & LWP. 
I try to search AbeBooks for the book "Codex Seraphinianus" from the main page (AbeBooks). Here is the code that I am using: 


#!/usr/bin/perl -w

use strict;
use LWP

my $cookie_jar = HTTP::Cookies->new(file => "lwp_cookies.dat", autosave => 1);

my $browser = LWP::UserAgent->new;

$browser->cookie_jar($cookie_jar);


my $response = $browser->get('http://www.abebooks.com',
   ["sts" => "t",
    "an" => "",
    "tn" => "Codex Seraphinianus",
    "kn" => "",
    "isbn" => ""
   ]
);

die "Error: ", $response->status_line, "\n" unless $response->is_success;

my $out_file = "result_seraph.html"; # where to save it
open(OUT, ">$out_file") || die "Can't write-open $out_file: $!";

binmode(OUT);
print OUT $response->content;
close(OUT);



But this just sends me back the content of the search page not the result page. Anyone knows what the problems are? Anyone can show me a real working code of LWP post?  Thanks.