tralala: I grouped train station and truck stop, yes – I don’t know whether it’s necessary, never tried it without grouping.
However, I don’t think that it’s really necessary. Even grouped stations count as separate stations, in a certain way:
This is the train part of the station. (I get this only when clicking directly on the station graphic, not by clicking the symbol.) Nothing is waiting here, as the train with the goods has just departed, and the coal is waiting for the trucks. Also, you can see that the iron the train just delivered is moving from the train station along the road to the truck station.
This is the truck part, a few days later, also selected by clicking on the station itself, not the symbol. Note that it still retains its own name (“Church Stretton Annex”), although the whole station goes by “Ch. St. West”. The coal is waiting here, and you can also see the iron disappearing: It *is* moved over from the train station, which it would only do if there’s “demand” at the truck station, the little symbols are getting fewer as they arrive, but they never show up at the station as waiting.
Anyway: I think douglas is right here, that grouping mostly is for alleviating player’s OCD. 😉
Also, seeing the state in which TF currently is, I wouldn’t be surprised if there are some bugs preventing such a supply chain from working under certain conditions, or just giving the appearance that it doesn’t work, or whatever.