SudsLibrary in Robot Framework: Getting & Setting object attributes - soap

Question

I am working with the SudsLibrary for Robot Framework. Below is the Rq/Rs for the webservice I'm testing. You will also find the Robot Framework info and my comment on what's going on.
REQUEST
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:sec="http://localhost/ABC/Services/Security/">
<soapenv:Header/>
<soapenv:Body>
<sec:AuthUser>
<sec:userName>MyAdmin</sec:userName>
<sec:password>Password123</sec:password>
</sec:AuthUser>
</soapenv:Body>
</soapenv:Envelope>
RESPONSE
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:wsa="http://schemas.xmlsoap.org/ws/2004/08/addressing" xmlns:wsse="http://docs.ompum-open.org/wss/2004/01/ompum-200401-wss-wssecurity-secext-1.0.xsd" xmlns:wsu="http://docs.ompum-open.org/wss/2004/01/ompum-200401-wss-wssecurity-utility-1.0.xsd">
<soap:Header>
...
</soap:Header>
<soap:Body>
<AuthUserResponse xmlns="http://localhost/ABC/Services/Security/">
<AuthTicket>k3l5d9k6-3z53-8765-b512-df09as87</AuthTicket>
</AuthUserResponse>
</soap:Body>
</soap:Envelope>
*** Settings ***
Library SudsLibrary
*** Test Case ***
Check App Auth Ticket
Create Soap Client http://localhost/Services/Authentication.asmx?wsdl
${WSDLobj} Create Wsdl Object AuthUser
Set Wsdl Object Attribute ${WSDLobj} userName MyAdmin
Set Wsdl Object Attribute ${WSDLobj} password Password123
${result} Call Soap Method AuthUser ${WSDLobj}
log Result: ${result}
# Now get the specific element from the response
${AuthVal} Get Wsdl Object Attribute ${result} AuthTicket
log Auth Ticket: ${AuthVal}
Everything is successful in my test case Check App Auth Ticket until I call the SudsLibrary Get Wsdl Object Attribute keyword. The following error occurs: ValueError: Object must be a WSDL object (suds.sudsobject.Object). Why would I get an error when the object is created and is called successfully?
When I print out the ${result} variable, it is the value for AuthVal. However, I am wanting to explicitly extract a specific value / element from the web service response. I have other web service responses that will require me to parse this data for my end to end testing.