Hi Glider,
Truly your add-on looks wonderful. I can't get over the fantastic detail of all 9 Merlin-1c's at the base of the Falcon 9. Magnificent.
I had the same error as Dogsbd, but I did have stage.cfg and dll installed. So there's a little more to fix before your next release! In your Falcon 1 and 9 ini files, you call "module=...stage1" but don't have such a module existing. (You do have a "stage1" config file, but it's not enough...there has to be an appropriate dll.) I'd simply remove these "module" lines as they are not needed if you have stage.cfg and stage.dll installed. Vinka's multistage2 will take care of staging and discarded stage behavior with the stage dll.
Also, there was an incorrect module definition for the Falcon 9's satellite payload. Do you have a dll for that? As before, "Module" points to a cfg file, but the CFG file in this case simply refers to a DLL. If you've not got a separate DLL written for your satellite, why not use Vinka's other DLL, spacecraft3? Then you can replace your "module=Space_X_rockets\Satellites\Falcon-9_LEO_satellite" line in your payload section of falcon9 ini file with simply "module=spacecraft\spacecraft3", and write a short ini file for your satellite, and put it in the config\spacecraft directory. That's all you need to do.
See Vinka's spacecraft3 documentation for details!
Thank you,
MT