Since there is a large amount of oil deposits in my city, I chose to go into oil specialization.. I've plopped several oil wells and I make a fair amount of profit selling crude oil on the global market.
Now I want to go to the next level by making my oil into fuel or plastic. I already built a Petroleum HQ. However, I can't build the Refining Division (which is needing for the oil refinery which in turn makes plastic out of crude oil), it shows "Not Approved" without explicitly stating which requirement I'm missing. It also might be that I have to upgrade my HQ first, because it's showing a progress bar indicating that I must make a certain amount of profit. I tried selling more curde oil, but I have come to the point where I'm making more oil than the trade depot can sell. I've added more trade depots, but that doesn't seem to make any difference because only one depot is selling as far as I can tell. The others just get their storage filled up.
So, any ideas? What am I missing here?