Parsing XML with multiple namespaces using PHP

parsing_xml_with_multiple_namespaces.php

<?php
/**
 * @author: Sohel Rana
 * @url: https://blog.sohelrana.me/parsing-xml-multiple-namespaces-using-php/
 * @license: MIT
 * Parsing XML with multiple namespaces using PHP
 */

$xmlString = "<en:Envelope xmlns:en=\"http://www.softcare.com/HIPAA/SC/Enrollment/0301\"
             xmlns:sc=\"http://www.softcare.com/HIPAA/SC/0203\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"
             xsi:schemaLocation=\"http://www.softcare.com/HIPAA/SC/0203 ../schema/types/common-types_0203.xsd http://www.softcare.com/HIPAA/SC/Enrollment/0301 ../schema/Enrollment_0301_rc2.xsd\">
    <en:EmployeeDetail>
        <en:SubscriberIdentifier>12234432</en:SubscriberIdentifier>
        <en:MemberLevelDates>
            <en:MaintenanceEffective format=\"CCYYMMDD\">20161202</en:MaintenanceEffective>
            <en:EmploymentBegin format=\"CCYYMMDD\">19960422</en:EmploymentBegin>
        </en:MemberLevelDates>
        <en:MemberDetail>
            <en:Person>
                <sc:LastName>TEST</sc:LastName>
                <sc:FirstName>EE1</sc:FirstName>
                <sc:MiddleName>A</sc:MiddleName>
            </en:Person>
            <en:Identification>
                <en:SSN>122332213</en:SSN>
                <en:MutuallyDefined>5819144b1defc67d771f172d</en:MutuallyDefined>
            </en:Identification>
            <en:DemographicInformation>
                <en:DateOfBirth format=\"CCYYMMDD\">19520706</en:DateOfBirth>
                <en:GenderCode>F</en:GenderCode>
                <en:MaritalStatusCode>I</en:MaritalStatusCode>
            </en:DemographicInformation>
            <en:PaymentInformation>
                <sc:AddressLine1>123 street</sc:AddressLine1>
                    <sc:City>test city</sc:City>
                    <sc:ProvinceOrStateCode>MA</sc:ProvinceOrStateCode>
                    <sc:PostalOrZipCode>02571</sc:PostalOrZipCode>
            </en:PaymentInformation>
            <en:JobTitle>Administrative Support</en:JobTitle>
        </en:MemberDetail>
        <en:MailingAddress>
            <sc:AddressLine1>123 street</sc:AddressLine1>
            <sc:City>test city</sc:City>
            <sc:ProvinceOrStateCode>MA</sc:ProvinceOrStateCode>
            <sc:PostalOrZipCode>02571</sc:PostalOrZipCode>
        </en:MailingAddress>
        <en:DisabilityInformation/>
    </en:EmployeeDetail>
</en:Envelope>";

$xml = simplexml_load_string($xmlString, NULL, NULL, "http://www.softcare.com/HIPAA/SC/Enrollment/0301");

// Getting EmployeeDetail data
var_dump($xml->EmployeeDetail);

// Does't contain any data
var_dump($xml->EmployeeDetail->MemberDetail->Person);
var_dump($xml->EmployeeDetail->MemberDetail->PaymentInformation);

// Getting Person and PaymentInformation data by using children.
$personInfo = $xml->EmployeeDetail->MemberDetail->Person->children('http://www.softcare.com/HIPAA/SC/0203');
$paymentInfo = $xml->EmployeeDetail->MemberDetail->PaymentInformation->children('http://www.softcare.com/HIPAA/SC/0203');
var_dump($personInfo);
var_dump($paymentInfo);

I'm getting error