Great Mercantile Port--Question

[Europa Romanorum]

Hi everyone,

I'm a long time lurker here, and a user of the awesome mod that is Europa Barbarorum, but something has perplexed me enough to sign up:

Playing as Roma, although this may be the case with other factions as well, in the trade summary for cities with Great Mercantile Ports part of the trade is faded--as if it will become solid after a building, say, the Great Mercantile Port, is created; it never does. Are the Great Mercantile Ports useless? Is it only a problem with the trade scroll? Or perhaps I need to do something else before I can get that extra trade?

Just to clarify, I have been playing with 1.0