Campaign graphics - traffic

[mindw]

you can see that there are transports on the road, moving between settlements, and ships on the sea, sailing between ports, and if you move mouse on the road then you see
"The amount of traffic indicates the amount of trade. ...."
The problem is that I dont see any ships or transports anymore. Does anybody know how to switch that on?

[Griwild]

I know this answer comes extremly late. Probabely you don't have the problem anymore.
I just write this in case somebody else has this problem and finds this thread looking for the answer.

The problem is the unit size, that you can set in the game options!
If it is set to "small units" you won't see any traffic on the roads or the sea routes on the campaign map!

Note:
You can start a campaign with small units; after you saved the campaign for the first time, leave the current game, set the unit size to medium, large or huge, and load your game again. You'll still play with small units, but now you can see all the wagoons and small ships that indicate your trade!