What am I missing here?

Im playing as the Pols, and am trying to trade with the Danes.
I have a port, merchant, and shipyard in my province. The Danes have a port in Denmark that Im trying to trade with. I have a ship in the Baltic and another off the coast of Denmark, so the trade route is linked. Yet when I click on my port it tells me that its generating 0 income.

I've only had the set-up for 3 turns, so does the process take a few years to begin working?
Also, Im neutral with the Danes. Do I need to Ally 1st?


any help would be appreciated


r