Service callback can't hit lower environment

Hi All, We started implementing ESL in our company and we have two accounts, one is for production and the other used in lower environment, (dev and test), the problem is that, the sandbox cannot reach our REST service in test environment, (we did not test in production yet), it fails every time. Here are the steps we did to setup the environment: 1) - We've installed the following SSL certificate in our weblogic server https://docs.esignlive.com/content/c_integrator_s_guide/introduction/system_requirements.htm 2) - We've setup a reverse proxy in our test environment, thus it's now accessible by external apps. So my questions are: 1) Are we missing some extra configuration? 2) Is there a SSL certificate to sandbox and one to production environment? (which in this case we might be installing the wrong one) 3) Do you have some tool that could give us some more insights? Note: Our java implementation doesn't contain any configuration regarding SSL or whatever. It's only a REST service, which works if we call through external tool like SoapUI. Here's the REST java code.

@RequestMapping(method = RequestMethod.POST)
public void callback(HttpServletRequest req, HttpServletResponse resp) throws ESLException {
	long startTime = LoggerUtil.logEnter(ESLServiceNotificationController.class, CALLBACK_METHOD);
	String packageId = "";
	
	try {
		resp.setContentType("text/html");
		resp.setStatus(HttpServletResponse.SC_OK);
		
		String aux = "";
		StringBuilder builder = new StringBuilder();
		
		while ((aux = req.getReader().readLine()) != null) {
			builder.append(aux);
		}
		
		JSONObject json = new JSONObject(StringUtils.deleteWhitespace(builder.toString()));
		packageId = json.get("packageId").toString();
		String sessionUser = json.get("sessionUser").toString();
		String name = json.get("name").toString();
		
		ESLEventListenerDTO eslEventListenerDTO = new ESLEventListenerDTO(name, sessionUser, packageId);
		LoggerUtil.logInfo(ESLServiceNotificationController.class, "Payload: " + eslEventListenerDTO.toString());
		
		esignServicesLocator.getESLNotificationService().processNotification(eslEventListenerDTO);
	} catch (JSONException e) {
		esignServicesLocator.getESLNotificationService().processExceptionNotification(packageId, e.getMessage());
		LoggerUtil.logError(ESLServiceNotificationController.class, "An exception during JSON parser - " + e.getMessage(), e);
	} catch (Exception ex){
		esignServicesLocator.getESLNotificationService().processExceptionNotification(packageId, ex.getMessage());
		LoggerUtil.logError(ESLServiceNotificationController.class, ex.getMessage(), ex);
	} finally {
		LoggerUtil.logExit(ESLServiceNotificationController.class, CALLBACK_METHOD, startTime);
	}
}