Cannot make simple REST call to API

Hello,
I am in the process of converting some python code that calls a REST webservice to soapUI test case. For some reason each time I try to call the webservice, I get a pop up 'Authentication Required' (see screenshot). The python code works without a problem. I am not sure what I am doing wrong here. I have tried passing the params as query, post body, etc with no success. This is quite urgent!



This is the python code

def test_update_changepassword (self):
        response, content = self.rest.make_request('POST', self.rest_endpoint_admin, 'password=changeme')

 def make_request(self, method, uri, body='', urlparam=''):
        '''
        Make a HTTP request to an endpoint

        @type  method: string
        @param method: HTTP valid methods: PUT, GET, POST, DELETE
        @type  uri: string
        @param uri: URI of the REST endpoint
        @type  body: string or dictionary or a sequence of two-element tuples
        @param body: the request body
        @type  urlparam: string or dictionary or a sequence of two-element tuples
        @param urlparam: the URL parameters

            >>> r = SplunkRest('https://localhost:8089')
            >>> r.make_request('POST', '/services/receivers/simple', urlparam={'host': 'foo'}, body="my event")

        '''
        if type(body) != str:
            body = urllib.urlencode(body)
        if type(urlparam) != str:
            urlparam = urllib.urlencode(urlparam)
        if urlparam != '':
            url = "%s%s?%s" % (self.uri_base, uri, urlparam)
        else:
            url = "%s%s" % (self.uri_base, uri)

        try:
            response, content = self.http.request(url, method, body=body, headers=self.headers)
        except ssl.SSLError, se:
            raise AssertionError, "ssl.SSLError (REST call hangs): %s" % str(se)

        request = {'method': method, 'url': url, 'body': body,
                   'auth': '%s:%s' % (self.username, self.password), 'header': self.headers}
 
        self.logger.info("Request => %s" % request)
        return response, content

The output of

self.logger.info("Request => %s" % request)

is

Request => {'body': 'password=changeme', 'url': 'https://127.0.0.1:8089/services/authentication/changepassword/admin', 'method': 'POST', 'auth': 'admin:changeme', 'header': {'content-type': 'text/xml; charset=utf-8'}}

I have attached the soapui project for reference

Thanks

Ali