$Doc->saveXML()的问题

[lxj_com2006]

$Doc->saveXML()的问题:

$txtUserName = $_POST['txtUserName'];
$txtPassword = $_POST['txtPassword'];

$OutXMLCmd = $XMLHeadStr.$XMLLogin;

$XMLDoc = new DOMDocument();
$XMLDoc->loadXML($OutXMLCmd);//$XMLHeadStr.

$XMLDoc->getElementsByTagName("loginName")->item(0)->nodeValue = $txtUserName."登陆";
$XMLDoc->getElementsByTagName("Pwd")->item(0)->nodeValue = $txtPassword;

echo "OutXMLCmd=".htmlentities($XMLDoc->saveXML())."<br/><br/>";
$ReXMLStr = $SYSSocket->SendXMLCmd($XMLDoc->saveXML());

$XMLDoc->loadXML($ReXMLStr);
echo $XMLDoc->saveXML; //这里输出还是前面的XML,好象执行loadXML第二次没有作用,问高手.