バッチリクエストでResponseGroupを指定すると、内部サーバーエラーになる

amazon 
#!/usr/bin/perl
use strict;
use warnings;
use URI;
use LWP::UserAgent;

my $uri = URI->new("http://webservices.amazon.co.jp/onca/xml");
$uri->query_form(
    Service                           => "AWSECommerceService",
    Version                           => "2008-04-07",
    AWSAccessKeyId                    => $access_key,
    Operation                         => "ItemSearch",
    "ItemSearch.Shared.SearchIndex"   => "Books",
    "ItemSearch.Shared.ResponseGroup" => "Small",
    "ItemSearch.Shared.Keywords"      => "perl",
    "ItemSearch.0.ItemPage"           => "1",
    "ItemSearch.1.ItemPage"           => "2",
);
my $ua = LWP::UserAgent->new;
my $res = $ua->get($uri);
print $res->code, "\n";

500

とりあえず、Operationを"ItemSerach,ItemSearch"することでエラーを回避できる。