I have installed the Sudbahn Rsslo scenario, but when I try to start a route, I get a warning "impossible to load rail vehicle OBB 4024. I have, for train simulators, the Steam library in an external HD" G, it only appears the landscape but not the train.
Sometimes you have to buy the RSSLO version even that you have the steam version. I had to buy the ÖBB 1042 loco from RSSLO even I had it from Steam to make some RSSLO scenarios work.
