Problemer med at læse kildekode fra en anden webside

PHP kode 

 <?php
   function do_post_request($url, $data, $optional_headers = null)
   {
      $params = array('http' => array(
                   'method' => 'POST',
                   'content' => $data
                ));
      if ($optional_headers !== null) {
         $params['http']['header'] = $optional_headers;
      }
      $ctx = stream_context_create($params);
      $fp = @fopen($url, 'rb', false, $ctx);
      if (!$fp) {
         throw new Exception("Problem with $url, $php_errormsg");
      }
      $response = @stream_get_contents($fp);
      if ($response === false) {
         throw new Exception("Problem reading data from $url, $php_errormsg");
      }
      return $response;
   }
 
 
 $url = 'http://din.url/her';
 
 $data = array(
   'post_variabel_navn'=>'postvariabel indhold', 
   'anden_post_variabel'=>'noget andet variabelt indhold'
 );
 
 $data = http_build_query($data);
 
 try
 {
   //hvis det virker, echo'er den siden
   echo do_post_request($url, $data);
 }
 catch(Exception $e)
 {
   //ellers echo'er den fejlen
   echo $e->getMessage();
 }
 
 ?>