Problem with a fictitious Heliport designed with ADE ?

[gerodcray]

Hello,
As a training for using ADE I designed a small fictitious heliport. The choosen OACI code was MTL and I got no problem before using the ADE tool for checking priority : the message was "the airport identifier code entered is not available". I was surprised as I have had no problem before with this code. Nevertheless I thought it was perhaps because four characters were needed for the OACI code and I made the change MTL to MTLG in the xml file and for all folders and files containing the characters MTL. Everything was OK and I could continue modifying and using the scenery with P3Dv4. But I always have the message "the airport identifier code entered is not available" when trying to analyse the priority. I guess I missed doing something but what ? That is the question. Thank you very much for helping.
Best regards
gerodcray

PS as the country code is LF there is no airport/heliport with the code MTL ou MTLG