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The paucity of any additional information leads to people having to guess
where your problem may lie.
Congratulations on getting as far as you have using the command line tool.
Which one are you using?(3ds2kexbeta is the one to use to export airport objects).
My Guess is your tga texture filename is too long!,should be No more than 12 Characters long.
eg 12345678.tga and must be a power of 2 for example{512*512 or 2048*2048}pixel dimensions.
Only problem i have had with converter is the Ferris Wheel object which refuses 2
work, even tho recognized by RealFlight as a valid Ferris Wheel Airport Object
Import.
There is a Poly Limit of 6000 without a Collision Mesh & 20000 With, using the
converter.