simplexml_load_string显示空对象php

I am new to xml. I have string response from api as :

<PPResponse Result="000" Key="110308f9-6b67-422b-9dee-9c9da77d8197">
    <ResultMessage>Operation is succesfully completed</ResultMessage>
    <UtilityInfo>
        <UtilityCode>123</UtilityCode>
    </UtilityInfo>
    <BillInfo>
        <Bill>
            <BillNumber>110308f9-6b67-422b-9d13-1c9da77d8197</BillNumber>
            <DueDate>2015-12-10T07:31:44</DueDate>
            <Amount>100</Amount>
            <ReserveInfo>test</ReserveInfo>
            <BillParam>
                <mask>4</mask>
                <commission type="0" val="0.00" op="-" paysource="1" />
            </BillParam>
            <RefStan>123123123123</RefStan>
        </Bill>
    </BillInfo>
</PPResponse>

I try to convert it to xml object like this:

`

libxml_use_internal_errors(true);
        $simple_xml = simplexml_load_string($response);
        if ($simple_xml === false) {
            echo "Failed loading XML
";
            foreach(libxml_get_errors() as $error) {
                echo "\t", $error->message;
            }
            echo 'hi'; exit();
        }
        echo 'pass';    exit();`

It displays pass. Now, the error is that, when I dd($simple_xml), I get nothing as:

libxml_use_internal_errors(true); $simple_xml = simplexml_load_string($response); if ($simple_xml === false) { echo "Failed loading XML "; foreach(libxml_get_errors() as $error) { echo "\t", $error->message; } echo 'hi'; exit(); } dd($simple_xml)

I need to access the keys and values from the string after converting it to xml object. I think, regex is also solution, but I need to do through xml object.

Any help would be highly appreciated. Its a sort of emergency.

This works fine for me:

libxml_use_internal_errors(true);

$xml = simplexml_load_string($response);
// var_dump($xml); this will output the xml object just fine

if ($xml !== false) {
    echo "Successfuly loaded the XML" . PHP_EOL;
    print "Message: " . $xml->ResultMessage . PHP_EOL;
    print "Utility code: " . $xml->UtilityInfo->UtilityCode . PHP_EOL;
    print "Bill Amount: " . $xml->BillInfo->Bill->Amount . PHP_EOL;
}
else{
    echo "Failed loading the XML" . PHP_EOL;
    foreach(libxml_get_errors() as $error) {
        echo "\t", $error->message;
    }
}

Will display

Successfuly loaded the XML
Message: Operation is succesfully completed
Utility code: 78
Bill Amount: 0

use the below code to test for BOM sequence and remove it if it exists

$bom = pack("CCC", 0xef, 0xbb, 0xbf);
if (0 === strncmp($response, $bom, 3)) {
    echo "BOM detected - file is UTF-8" . PHP_EOL;
    $response = substr($response, 3);
}
// or
$response = str_replace("\xEF\xBB\xBF",'',$reponse);