Just to expand a bit and I'm not sure if this is relavent in your case, but in a totally different scenario I was getting a strange InvalidDefinitionException. It turns out that the functionality that adds/updates WSDL always assumes a HTTP 200 OK response and that the reply contents is a WSDL document, thus if ever some other response is returned e.g. HTTP 401 Unauthorised, the add/update functionality ignores it and tries to process the associated reply contents as WSDL when it is not, hence the unexpected InvalidDefinitionException. This issue was reproduced by SmartBear support and logged as defect number SOAP-5946.
I also discoved, there is an problem with the WSDL "Update Definition" functionality, if a WSDL fails to import because there is a genuine invalid WSDL issue, once the WSDL is corrected Ready API still thinks that there is a problem and reports invalid WSDL. The only way to successfully update the WSDL was to exit and restart Ready API. This issue was also reproduced by SmartBear support and logged as defect number SOAP-5947