City connections not registering?

[Philosophia]

I'm sorry if this is a stupid thing, but I was just playing around with Carthage and settled some cities on the coast expecting the harbor to connect once they were settled. However they didn't and I got no bonus gold for cities on the coast. Is this a bug or did I do something stupid? (I've never played Carthage before)

 

[Petiscator]

Did you research "The Wheel"? It is a requisite for having City Connections.