In Making up for it in the Middle East in the Microsoft Flight Simulator X segment of the Forum, I mentioned the difficulty I was having in trying to install FS Group's Orumiyeh Airport.
I have now been able to install it.
I made a further attempt the same day as my exchange of emails with the developer but was unsuccessful.
I decided to give up at that stage.
However, some days later my youngest son (whose knowledge of computers is far greater than mine) was visiting us and he offered to try to install it.
He could find no trace of the airport having been installed on any of my ten previous attempts. All that I had to show for those attempts were the four page pdf manual.
He tried installing it. My flight sim is in my E Drive and my add-on airports go to E:\Mircrosoft Flight Simulator X\addon scenery. He chose that path at the installation choice stage and the result was the same lack of success as I had consistently experienced. The path was greyed out. He then decided to accept the default path offered of E:\APPDIR which the product installer was showing. The product installed to the E Drive but no trace of it could be found in any of the Microsoft FSX sub-folders or in the Scenery Library when I started FSX. Why didn't it go there?
However, when I selected Orumiyeh in Airports in Free Flight, I got the FS Group product as the version of the airport (rather than any Default version, ie identical to the product screenshots) and was able to fly it.
How can an add-on airport appear nowhere in the FSX path files or in the Scenery Library but be there and operational when flying in FSX?