why Exception is null in android

why Exception is null in android

httpTransport.call this line of code have excetion, But ex is null
private static String CallServiceMethod(String methodName,String Json)
throws Exception {
Object response = null; try {
SoapObject request = new SoapObject(WSDL_TARGET_NAMESPACE,methodName);
PropertyInfo propertyInfo = new PropertyInfo();
propertyInfo.setName("Json");
propertyInfo.setValue(Json);
propertyInfo.setType(String.class);
request.addProperty(propertyInfo);
SoapSerializationEnvelope envelope = new
SoapSerializationEnvelope(SoapEnvelope.VER12);
envelope.dotNet = true;
envelope.setOutputSoapObject(request);
HttpTransportSE httpTransport = new
HttpTransportSE(SystemConfiguration.ServiceUrl);
httpTransport.call(WSDL_TARGET_NAMESPACE + methodName, envelope); //Error
response = envelope.getResponse();
}
catch (Exception ex)
{
//TODO:Log
String x = ex.getMessage(); //why ex is null???
}
return response.toString();
}