GerdD,
Please, disregard my latest message, I tought the missing XML header in your file might have been a problem, but I haven't checked for it.
I made another test, with exactly the same file you sent me, without the header, and IT WORKS OK! The installer IS able to fix an EXE.XML, even without the header, and there are no problems with GoFlight lines.
However, I need you to do me a favour: can you try again on your system, with the XML file with the missing header, and install the Stand-Alone Addon Manager, being absolutely sure it's the current version we have online right now (it has been updated on KLAS release date ) ?
It's best to use the Stand-Alone version, so there are no issues with uninstalling sceneries, but the XML modying routine is exactly the same so, it's a check that is valid for all installers.
Because, the XML fixing stuff is made launching an included executable program we include with the installer so, if this has failed on your system, it might be a reason why the XML with the missing header hasn't been fixed, and it might be interesting to know why, if this is the case.