Responses for WSDL services are typically XML, defined in the service's WSDL. Some WSDL services return HTML. MashZone NextGen currently only supports HTML results for WSDL services if the HTML payload is wrapped in a CDATA section. For WSDL services that do not use a CDATA section to wrap HTML, you can use a mashup to invoke the service and handle the response properly. See Wrapping WSDL Web Services That Return HTML Results for more information.