Hello, hope i can help.
When you say trade commodity, i assume you mean one of the trade goods like Diplomatic Translators or Micro Repair Bots. These have no bearing on the actually trade via ships in the game. These are for you to trade via the Foreign Relations screen when talking to another empire, or keep for your self. I never trade away Diplo Trans or Aphrodesiac.
Onto trade via freighters. Once you research trade and get the freighter are you using the default ship or building your own, if your own be sure to put the Trade module on the ship, it's an empty hull without it. Once built and launched simply select your ship and right click on the AI planet you wish to trade with.
The only reason it would not work is if you are,
A) At war with that AI, they will throw things at you and tell you where to go..
If they have placed a trade embargo on you. Not that i have seen the AI do this....
C) The planet is out of range of your ship
Also once you reach your trade limit, though this would not be the case as in hand.
A little trick i do is to pick a minor race to trade with, preferably one that you can protect from everyone else. That way when you go on your mission to destroy the major races you won't be losing any trade income....
Hope this helps
