Centos安装的PHP总是包XML错误，求解救

错误信息
PHP Fatal error:  Call to a member function createCDATASection() on a non-object in api.class.php on line 67
PHP版本
PHP 5.3.3 (cli) (built: Jul  9 2015 17:39:00)
Copyright (c) 1997-2010 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies
已安装组件
bz2   calendar    Core   ctype   curl   date   dom   ereg   exif   fileinfo   filter   ftp   gd  gettext    gmp   hash   iconv   json   libxml   mbstring    mcrypt    mysql   mysqli  
openssl     pcntl   pcre   PDO   pdo_mysql   pdo_sqlite   Phar    readline    Reflection   session    shmop   SimpleXML     sockets   SPL     sqlite3     standard    
tokenizer    wddx    xml      xmlreader   xmlwriter     xsl      zip    zlib
报错的代码
protected static function data2xml($xml, $data, $item = 'item') {
        foreach ($data as $key => $value) {
            is_numeric($key) && $key = $item;
            if(is_array($value) || is_object($value)){
                $child = $xml->addChild($key);
                self::data2xml($child, $value, $item);
            } else {
                if(is_numeric($value)){
                    $child = $xml->addChild($key, $value);
                } else {
                    $child = $xml->addChild($key);
                    $node  = dom_import_simplexml($child);
                    $cdata = $node->ownerDocument->createCDATASection($value);//此行报错
                    $node->appendChild($cdata);
                }
            }
        }
    }