FlightXML2 Enroute service responds with NULL

I am trying to retrieve data for the Airport “YNEN” via the Enroute() web-service method.
I am using .NET framework 4.0.
When I make the Enroute(“YNEN”, 50,NULL,0) web-service method request I get a response EnrouteStruc consisting of null values.
I have tried Enroute(“YPDN”, 50, NULL,0)web-service method request and it responds with EnrouteStruc consisting of data as expected.
Your assistance with this matter would be greatly appreciated.

At the time of the query did you notice any enroute flights to YNEN at https://flightaware.com/live/airport/YNEN?

To Whom it may concern

Yes, there were indeed flights to YNEN which were able to be viewed from your website but they could not be accessed via the Flightaware services.

Regards,

Hubert Casse