Sounds like you are using a wrong version. Did you get it from factoriomods.com? Those are outdated/broken, if i could i'd delete them from the site, but i can't.
Use this one: https://github.com/Choumiko/RailTanker/ ... _1.1.3.zip

That worked, Thanks

I'm having some problems with this mod, i'm sure its just because I don't know what i'm doing. When I try to start a game with this mod I get __RailTanker__/control.lua:130: attempt to index global 'game' (a nil value). How do I fix this?