Call to undefined method DOMElement::save()

[veaudaux]

Stripped down version of my code:

 

 $xmlSubmission = simplexml_load_file($submissionDirectory . "/submissions.xml");

$newSubmission = $xmlSubmission->addChild('submission');
$newSubmission->addChild('title', 'XML Add Test');
$newSubmission->addChild('author_id', 'me');

$dom_xmlSubmission = dom_import_simplexml($xmlSubmission);
$dom = new DOMDocument('1.0');
$dom_xmlSubmission = $dom->importNode($dom_xmlSubmission, true);
$dom_xmlSubmission = $dom->appendChild($dom_xmlSubmission);

$test = $dom_xmlSubmission->save($submissionServerPath . "submissions2.xml");

 

This outputs a file with nothing but "<?xml version="1.0"?>" and spits an error "Fatal error: Call to undefined method DOMElement::save()". Now what?