PHP DOMDocument getElementsByTagname?

Cette conduite est moi dingue... je veux juste ajouter un autre img nœud.

$xml = <<<XML
<?xml version="1.0" encoding="UTF-8"?>
<gallery>
    <album tnPath="tn/" lgPath="imm/"  fsPath="iml/" >
    <img src="004.jpg" caption="4th caption" />
    <img src="005.jpg" caption="5th caption" />
    <img src="006.jpg" caption="6th caption" />
</album>
</gallery>
XML;

$xmlDoc = new DOMDocument();
$xmlDoc->loadXML($xml);

$album = $xmlDoc->getElementsByTagname('album')[0];
//Parse error: syntax error, unexpected '[' in /Applications/XAMPP/xamppfiles/htdocs/admin/tests/DOMDoc.php  on line 17
$album = $xmlDoc->getElementsByTagname('album');
//Fatal error: Call to undefined method DOMNodeList::appendChild() in /Applications/XAMPP/xamppfiles/htdocs/admin/tests/DOMDoc.php on line 19

$newImg = $xmlDoc->createElement("img");
$album->appendChild($newImg);

print $xmlDoc->saveXML();

Erreur:

source d'informationauteur FFish