erros em script

oi gente,

dessa vez peço que me ajudem com algo simples: dentro do script abaixo existe algum erro que possa causar o erro 500? sempre que tento rodar da esse erro.

<?php
$accountKey = 'a api key'; //keys changed
$ServiceRootURL = 'https://api.datamarket.azure.com/Bing/Search/';
$WebSearchURL = $ServiceRootURL . 'Image?$format=json&$Top=10&Adult=%27Strict%27&ImageFilters=%27Size%3aMedium%27&Query='; //top5
// $WebSearchURL = $ServiceRootURL . 'Image?$format=json&Adult=%27Strict%27&ImageFilters=%27Size%3aMedium%27&Query='; //get max
$context = stream_context_create(array(

 'http' => array(
 'method'=>'GET',
 // 'proxy' => 'tcp://127.0.0.1:8888',
 // 'proxy' => 'tcp://127.0.0.1:8080',
 'request_fulluri' => true,
 'header' => "Authorization: Basic " . base64_encode($accountKey . ":" . $accountKey)
 )
));

/* SEARCH SETTINGS
------------------------------------------------------------------------------------------------ */

$keyphrase = '"cars"';

echo('<h3>'.$keyphrase.'</h3>');

//build search query

$request = $WebSearchURL . urlencode( '\'' . $keyphrase . '\'');
// debug($request);

$response = file_get_contents($request, 0, $context);
$jsonobj = json_decode($response);
// debug($jsonobj);

echo('<ul ID="resultList">');
foreach($jsonobj->d->results as $value)

{

 if ($value->ContentType == 'image/jpeg')
 {
 echo('<li class="resultlistitem" style="font-size:12px;float:left;padding:15px;border:1px solid blue;list-style:none;">');
 echo('<a href="' . $value->MediaUrl . '">');
 echo('<img src="' . $value->Thumbnail->MediaUrl. '" width="'.$value->Thumbnail->Width.'" height="'.$value->Thumbnail->Height.'" /></a>');
 echo('<h2>File information:</h2>');
 echo('<ul>');
 echo('<li><strong>Id:</strong> '.$value->ID.'kb</li>');
 echo('<li><strong>Title:</strong> '.$value->Title.'kb</li>');
 echo('<li>'.imgSeoPrettyFilename($value->Title).'.jpg</li>');
 echo('<li><strong>Filesize:</strong> '.round(($value->FileSize/1000), 2).'kb</li>');
 echo('<li><strong>Height:</strong> '.$value->Height.'px</li>');
 echo('<li><strong>Width:</strong> '.$value->Width.'px</li>');
 echo('<li><strong>Source:</strong> '.$value->SourceUrl.'</li>');
 echo('<li><strong>Filetype:</strong> '.$value->ContentType.'</li>');
 echo('</ul>');
 echo('</li>');
 }
}
echo('</ul>');
?>

obrigado.