尝试在 xml 文件 - php 脚本中保存日期时出现 DOMDocument 错误

将表单数据保存到xml时遇到一点问题。我尝试向 xml 对象添加新元素 （$ukey），但它在变量$ukey上给了我一个错误。 $newItem->appendChild（$xml->createElement（'ukey'， $ukey））;

// Script by Fred Fletcher, Canada.
$fname = $_POST['name'];
$lname = $_POST['email'];
$location = $_POST['cat'];
$report = $phone;
$description = $_POST['content'];
$ukey = date("dmYHis");

$xml = new DOMDocument('1.0', 'utf-8');
$xml->formatOutput = true;
$xml->preserveWhiteSpace = false;
$xml->load('/home/mysite/public_html/file.xml');
$element = $xml->getElementsByTagName('reports')->item(0);
$timestamp = $element->getElementsByTagName('timestamp')->item(0);
$fname = $element->getElementsByTagName('fname')->item(0);
$lname = $element->getElementsByTagName('lname')->item(0);
$location = $element->getElementsByTagName('location')->item(0);
$report = $element->getElementsByTagName('report')->item(0);
$description = $element->getElementsByTagName('description')->item(0);
$ukey = $element->getElementsByTagName('ukey')->item(0);
$newItem = $xml->createElement('reports');
$newItem->appendChild($xml->createElement('timestamp', date("F j, Y, g:i a",time())));;
$newItem->appendChild($xml->createElement('fname', $_POST['name']));
$newItem->appendChild($xml->createElement('lname', $_POST['email']));
$newItem->appendChild($xml->createElement('location', $_POST['cat']));
$newItem->appendChild($xml->createElement('report', $phone));
$newItem->appendChild($xml->createElement('description', $_POST['content']));
$newItem->appendChild($xml->createElement('ukey', $ukey));
$xml->getElementsByTagName('entries')->item(0)->appendChild($newItem);
$xml->save('/home/mysite/public_html/file.xml');

这是错误

Warning: DOMDocument::createElement() expects parameter 2 to be string, object given in /home/mysite/public_html/wp-content/themes/twentytwelve/myform.php on line 214
Catchable fatal error: Argument 1 passed to DOMNode::appendChild() must be an instance of DOMNode, null given, called in /home/mysite/public_html/wp-includes/template-loader.php on line 47 and defined in /home/mysite/public_html/wp-content/themes/twentytwelve/myform.php on line 214

和 xml 示例

<?xml version="1.0" encoding="UTF-8"?>
<entries>
  <reports>
   <timestamp>September 19, 2013, 11:45 am</timestamp>
   <fname>John Snider</fname>
   <lname>mailATemail.com</lname>
   <location>156</location>
   <report>08974545153</report>
   <description>jhsdhfsdfgsdtasrgsfgasf</description>
   <ukey>156152</ukey>
  </reports>
</entries>

我需要将其更改为字符串还是有什么问题？

澄清一下，在我添加之前脚本运行良好$ukey

谢谢