Authorization Error When Calling An Oracle 11g Web Service

CREATE OR REPLACE FUNCTION ws_call
    RETURN VARCHAR2
AS
    service_             SYS.UTL_DBWS.service;
    call_                SYS.UTL_DBWS.CALL;
    service_qname        SYS.UTL_DBWS.qname;
    port_qname           SYS.UTL_DBWS.qname;
    xoperation_qname     SYS.UTL_DBWS.qname;
    xstring_type_qname   SYS.UTL_DBWS.qname;
    response             SYS.XMLTYPE;
    request              SYS.XMLTYPE;
BEGIN
--sys.utl_dbws.set_http_proxy('www-proxy:8080');
    service_qname    := SYS.UTL_DBWS.to_qname(NULL, 'WSTEST');
    service_         := SYS.UTL_DBWS.create_service(service_qname);
    call_            := SYS.UTL_DBWS.create_call(service_);
    SYS.UTL_DBWS.set_target_endpoint_address
                        (call_,
                         'http://10.0.1.23:8080/orawsv/NEUTRINO_WS/WSTEST'
                        );
    SYS.UTL_DBWS.set_property(call_, 'SOAPACTION_USE', 'TRUE');
    SYS.UTL_DBWS.set_property(call_,
                              'SOAPACTION_URI',
                              'http://10.0.1.23:8080/orawsv/NEUTRINO_WS/WSTEST'
                             );
    SYS.UTL_DBWS.set_property(call_, 'OPERATION_STYLE', 'document');
    request          :=
        SYS.XMLTYPE
            ('<WSTEST xmlns=""></WSTEST>'
            );
    response         := SYS.UTL_DBWS.invoke(call_, request);
    RETURN response.EXTRACT('//WSTESTResult/child::text()',
                            'xmlns=""'
                           ).getstringval();
END;
/

- <definitions name="WSTEST" targetNamespace="http://xmlns.oracle.com/orawsv/NEUTRINO_WS/WSTEST" xmlns="http://schemas.xmlsoap.org/wsdl/" xmlns:tns="http://xmlns.oracle.com/orawsv/NEUTRINO_WS/WSTEST" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/">
- <types>
- <xsd:schema targetNamespace="http://xmlns.oracle.com/orawsv/NEUTRINO_WS/WSTEST" elementFormDefault="qualified">
- <xsd:element name="SVARCHAR2-WSTESTInput">
- <xsd:complexType>
  <xsd:sequence /> 
  </xsd:complexType>
  </xsd:element>
- <xsd:element name="WSTESTOutput">
- <xsd:complexType>
- <xsd:sequence>
  <xsd:element name="RETURN" type="xsd:string" /> 
  </xsd:sequence>
  </xsd:complexType>
  </xsd:element>
  </xsd:schema>
  </types>
- <message name="WSTESTInputMessage">
  <part name="parameters" element="tns:SVARCHAR2-WSTESTInput" /> 
  </message>
- <message name="WSTESTOutputMessage">
  <part name="parameters" element="tns:WSTESTOutput" /> 
  </message>
- <portType name="WSTESTPortType">
- <operation name="WSTEST">
  <input message="tns:WSTESTInputMessage" /> 
  <output message="tns:WSTESTOutputMessage" /> 
  </operation>
  </portType>
- <binding name="WSTESTBinding" type="tns:WSTESTPortType">
  <soap:binding style="document" transport="http://schemas.xmlsoap.org/soap/http" /> 
- <operation name="WSTEST">
  <soap:operation soapAction="WSTEST" /> 
- <input>
  <soap:body parts="parameters" use="literal" /> 
  </input>
- <output>
  <soap:body parts="parameters" use="literal" /> 
  </output>
  </operation>
  </binding>
- <service name="WSTESTService">
  <documentation>Oracle Web Service</documentation> 
- <port name="WSTESTPort" binding="tns:WSTESTBinding">
  <soap:address location="http://10.0.1.23:8080/orawsv/NEUTRINO_WS/WSTEST" /> 
  </port>
  </service>
  </definitions>