JohnOver the years I have tried mostly in vain to load routes onto SkyMap; mainly from navbox. Like you we ahd all the proper cables etc.
One thing I do recall is that if you use a PC with a genuine serial port, it seemed to work. With USB/Serial converter then it either half-worked or even said it had worked but when you looked for theroute file it was not there.
So you cd see if anyone locally has an old PC with original serial port.
Just a thought
David