Help Adding event with Perl

I'm a newbie to programming with Google APIs and can't
figure out why the following doesn't work and wondered
if anyone here could help. (I get a 400 Bad Request error.)

  use LWP::UserAgent;
  $ua = LWP::UserAgent->new;
  $ua->agent("MyApp/0.1 ");



  # Create a request
  my $req = HTTP::Request->new(POST =>
'http://www.google.com/calendar/feeds/default/private/full');
  $req->header(Authorization => "GoogleLogin auth=xxxxxx");
  $req->content(<<EOT);
<entry xmlns='http://www.w3.org/2005/Atom'
          xmlns:gd='http://schemas.google.com/g/2005'>
       <category scheme='http://schemas.google.com/g/2005#kind'

term='http://schemas.google.com/g/2005#event'></category>
       <title type='text'>Tennis with Beth</title>
       <content type='text'>Meet for a quick lesson.</content>
       <author>
                  <name>Gk</name>
                  <email>xxxx_email_xxxx@xxxxxxxxx</email>
       </author>
       <gd:transparency
value='http://schemas.google.com/g/2005#event.opaque'>
                                     </gd:transparency>
       <gd:eventStatus
value='http://schemas.google.com/g/2005#event.confirmed'>
                                     </gd:eventStatus>
       <gd:where valueString='Rolling Lawn Courts'></gd:where>
       <gd:when startTime='2006-09-10T08:00:00.000Z'
                      endTime='2006-09-10T10:00:00.000Z'></gd:when>
</entry>
EOT

  # Pass request to the user agent and get a response back
  my $res = $ua->request($req);

  # Check the outcome of the response
  if ($res->is_success) {
      print $res->content;
  }
  else {
      print $res->status_line, "\n";
  }