Difference between 2 versions of POST?

Hi,

I have tried to use 2 scripts which I think should do similar things, but the first one is working, while the second is not. Can you make some light and tell me what's the difference between them and why the second is not working?

1. The first:

use LWP::UserAgent;

my $ua = LWP::UserAgent->new;
my $req = HTTP::Request->new( POST => 'http://localhost/cgi-bin/post.pl' );
$req->header( content_type => 'application/json' );
$req->content( 'some json content' );
my $res = $ua->request( $req );
print $req->as_string;
print $res->as_string;

2. The second:

use LWP::UserAgent;

my $ua = LWP::UserAgent->new;
my $res = $ua->post( 'http://localhost/cgi-bin/post.pl', Content => 'some json content' );
$res->request->header( content_type => 'application/json' );
print $res->request->as_string;
print $res->as_string;


The file post.pl:
#!/usr/bin/perl

use strict;
use CGI;

my $query = CGI->new;
my $data = $query->param('POSTDATA');

print "Content-Type: text/html\n\n";
print "Content: $data\n";


The first gives the following result:

POST http://localhost/cgi-bin/post.pl
User-Agent: libwww-perl/6.02
Content-Type: application/json

some json content
HTTP/1.1 200 OK
Connection: close
Date: Mon, 05 Sep 2011 15:58:17 GMT
Server: Apache/2.2.15 (Win32) mod_perl/2.0.4-dev Perl/v5.10.1
Content-Type: text/html
Client-Date: Mon, 05 Sep 2011 15:58:17 GMT
Client-Peer: 127.0.0.1:80
Client-Response-Num: 1
Client-Transfer-Encoding: chunked

Content: some json content


While the second gives the following result:

POST http://localhost/cgi-bin/post.pl
User-Agent: libwww-perl/6.02
Content-Length: 17
Content-Type: application/json

some json content
HTTP/1.1 200 OK
Connection: close
Date: Mon, 05 Sep 2011 16:00:10 GMT
Server: Apache/2.2.15 (Win32) mod_perl/2.0.4-dev Perl/v5.10.1
Content-Type: text/html
Client-Date: Mon, 05 Sep 2011 16:00:10 GMT
Client-Peer: 127.0.0.1:80
Client-Response-Num: 1
Client-Transfer-Encoding: chunked

Content: 

So it doesn't print the POSTed content, because it doesn't seem to send that content, although $res->request->as_string shows that it sends it.

Please tell me what's wrong... why $res->request->as_string shows the content which is sent, but without beeing really sent.

Thank you.

Octavian