PHP operation XML appendchild (); not added success!

Xmlphpdom node

$xml = new DOMDocument(); $xml->load("test.xml"); $newNode=$xml->createElement('BBB');//一级节点$xmlLoc=$xml->createElement('CCC');//二级节点$xmlLoc = $xml->createTextNode('testlink3');//填充数据，疑点１//var_dump($xmlLoc);object(DOMText)#7 (0) { }$newNode->appendChild($xmlLoc);//null!!!//$postDom = $xml->getElementsByTagName("AAA"); $xml->appendChild($newNode);//postDom？疑点２$xml->saveXml();

How to always be empty ah, how to correctly generate the DOM node and inserted behind the file???
Want to insert the following into the end of the XML

Testlink3

Examples of XML content:



Testlink1
Testlink2
Want to add here

The above code no error, but no effect, did not add success!!!
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