transport empire help

[david smith]

try to carry coal,iron ore ect, it keeps telling me trains carry inefficient carriages, have 3 open box cars, 1 small open box car, 1 multi purpose carriage

 

[Gt city]

try to carry coal,iron ore ect, it keeps telling me trains carry inefficient carriages, have 3 open box cars, 1 small open box car, 1 multi purpose carriage

I do not know, i just installed, player beginning introduction and got 4 greenies. That's all.