That's the normal situation when you are trying to use an airplane that is not internally supported by GSX and doesn't come with a profile.
The iniBuilds A340 is not internally supported by GSX, not only because it came out after the latest GSX update, but mostly because it's only sold on the MS Marketplace and, to provide full internal support for it (including Seated Passengers), we would need a standard non-encrypted version of it. If the airplane would never sold outside the MS Marketplace, it would likely never had full support like Seated Passengers, but at least you should be able to use it with all basic features, if you find a GSX profile for it, I'm sure somebody must have made it.
