[Python] Python lxml xpath not working on some elements

I'm having trouble extracting a specific element text from a soap response. Other elements seems to be working fine.

I have tried the following:

Python 3.13.3 (main, Apr 8 2025, 13:54:08) [Clang 16.0.0 (clang-1600.0.26.6)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from lxml import etree
>>> xml = '''<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope">
... <soap:Body>
... <soap:Fault>
... <soap:Code>
... <soap:Value>soap:Sender</soap:Value>
... <soap:Subcode>
... <soap:Value xmlns:ns1="http://docs.oasis-open.org/wss/oasis-wss-wssecurity-secext-1.1.xsd">
... ns1:unauthorized
... </soap:Value>
... </soap:Subcode>
... </soap:Code>
... <soap:Reason>
... <soap:Text xml:lang="en">AccessResult: result: Access Denied | AuthenticationAsked: true |
... ErrorCode: IDP_ERROR:
... 137 | ErrorReason: null</soap:Text>
... </soap:Reason>
... <soapetail>
... <WebServiceFault xmlns="http://www.taleo.com/ws/integration/toolkit/2005/07">
... <code>SystemError</code>
... <message>AccessResult: result: Access Denied | AuthenticationAsked: true | ErrorCode:
... IDP_ERROR: 137 |
... ErrorReason: null</message>
... </WebServiceFault>
... </soapetail>
... </soap:Fault>
... </soap:Body>
... </soap:Envelope>'''
>>> root = etree.fromstring(xml)
>>> print(root)
<Element {http://www.w3.org/2003/05/soap-envelope}Envelope at 0x1032c4680>
>>> ns = { 'soap':'http://www.w3.org/2003/05/soap-envelope', 'ns1':'http://docs.oasis-open.org/wss/oasis-wss-wssecurity-secext-1.1.xsd"' }
>>> print(root.xpath('//soap:Subcode/soap:Value',namespaces=ns)[0].text)

ns1:unauthorized

>>> print(root.xpath('//soap:Reason/soap:Text',namespaces=ns)[0].text)
AccessResult: result: Access Denied | AuthenticationAsked: true |
ErrorCode: IDP_ERROR:
137 | ErrorReason: null
>>> print(root.xpath('//soapetail/WebServiceFault/message',namespaces=ns)[0].text)
Traceback (most recent call last):
File "<python-input-7>", line 1, in <module>
print(root.xpath('//soapetail/WebServiceFault/message',namespaces=ns)[0].text)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^
IndexError: list index out of range


For some reason, the message element text I can't get.

Appreciate any help.

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