Read value from XML within another XML: Mule - xpath

Question

I am making a SOAP webservice call and I get the below response. I want to read the value in internal XML, the value is 12345684 in 1234684 in the below XML.
I was able to get internal XML using #[xpath3('//:processaResponse /return[2]')], store it in a flow variable and #[xpath3('/AckReg/DataArea/PRegistration/PRDet/Person/IDSet/:ID[#schemeName="aid"]/text()')].
This works when I try an online parser, but it doesn't read the value in Mule.
Is there any way to extract 1234684 in oa:ID tag using one XPath.
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
<soapenv:Header>
<ns3:TXID xmlns:ns3="http://a.d.r.test.com/"></ns3:TXID>
<ns3:SESSIONID xmlns:ns3="http://a.d.r.test.com/"></ns3:SESSIONID>
</soapenv:Header>
<soapenv:Body>
<ns3:processaResponse xmlns:ns3="http://a.d.r.test.com/" xmlns:ns2="http://p.r.test.com/">
<return>Hi</return>
<return>
<?xml version="1.0" encoding="UTF-8"?>
<AckReg
xmlns="http://www.test.com/e/1" languageCode="en-US" releaseID="normalizedString" systemEnvironmentCode="test" versionID="normalizedString"
xmlns:oa="www.test.com/r/9"
xsi:schemaLocation="http://www.test.com/a/1 ../test/test.xsd">
<Apa>
<oa:CreationDateTime>2018-04-05</oa:CreationDateTime>
</Apa>
<DataArea>
<Ack>
<OArea>
<o:Sender>
<o:LID schemeAgencyName="testi" schemeName="Application ID">test</o:LID>
</o:Sender>
</OArea>
<OriginalActionVerb/>
</Ack>
<PRegistration>
<testids>
<IDSet schemeAgencyName="try">
<oa:ID schemeName="abcid">1234684</oa:ID>
</IDSet>
</testids>
<PRDet>
<Person>
<IDSet schemeAgencyName="try">
<oa:ID schemeName="aid">1364561</oa:ID>
</IDSet>
<IDSet schemeAgencyName="enada">
<oa:ID schemeName="Employee ID">adsad</oa:ID>
</IDSet>
</Person>
<User>
<oa:ID/>
</User>
</PRDet>
</PRegistration>
</DataArea>
</AckReg>
</return>
</ns3:processaResponse>
</soapenv:Body>
</soapenv:Envelope>

Answer 1

In your expressions you were missing namespace prefixes or namespace wildcards *: on some nodes - so your expressions failed.
Is there any way to extract 1234684 in oa:ID tag using one XPath.
Combining both of your partial expressions is possible with namespace wildcards:
//*:processaResponse/return[2]/*:AckReg/*:DataArea/*:PRegistration/*:testids/*:IDSet/*:ID[#schemeName='abcid']/text()
Or you can use an absolute path with namespace wildcards:
/*:Envelope/*:Body/*:processaResponse/return[2]/*:AckReg/*:DataArea/*:PRegistration/*:testids/*:IDSet/*:ID[#schemeName='abcid']/text()
Output in both cases:
1234684

Answer 2

You can even use XmlSlurper class using groovy script to fetch that respective value.
root = new XmlSlurper( false, true).parseText(payload).declareNamespace('soapenv':"http://schemas.xmlsoap.org/soap/envelope/")