php:  if($op == 'getallfriend')
{
header('Content-Type: text/xml');
$name=$_GET["email2"];
$query="select * from table_user_baseinfo";
$result=mysql_query($query,$conn) or die ("数据操作出错:".mysql_error());
// header('Content-type: text/xml;charset=GB2312');
// $row = mysql_fetch_array($result);
$rows = mysql_num_rows($result);
// echo "$rows ";

$xml="";
while($arrRow = mysql_fetch_assoc($result))
{
    $xml .= "<union_data>\n";
    $xml .= "<Data_userID>".$arrRow["userID"]."</Data_userID>\n";
    $xml .= "<Data_registerID>".$arrRow["registerID"]."</Data_registerID>\n";
    $xml .= "<Data_name>".$arrRow["name"]."</Data_bieming>\n";
    $xml .= "<Data_registetime>".$arrRow["registetime"]."</Data_registetime>\n";
    $xml .= "</union_data>\n";
}
echo "<?xml version=\"1.0\" encoding=\"GB2312\"?>\n";
echo "<data>\n";
echo $xml;
echo "</data>";
}
js:var data=http_request.responseXML.documentElement.getElementsByTagName("union_data");  // alert(data.length);
for(var i=0;i<1;i++){
var friend = data[i]; //得一个结点
        var userID = friend.getElementsByTagName("Data_userID")[0].firstChild.data; //取结点里的数据
        var registerID = friend.getElementsByTagName("Data_registerID")[0].firstChild.data;
        var name = friend.getElementsByTagName("Data_name")[0].firstChild.data;
        var registetime = friend.getElementsByTagName("Data_registetime")[0].firstChild.data;

document.getElementById("word1").innerHTML= userID;
document.getElementById("word2").innerHTML= registerID;
document.getElementById("word3").innerHTML= name;
document.getElementById("word4").innerHTML= registetime;
alert("go");
}

请问各位大侠,什么地方出错了啊??