I've been playing a bit as Prussia, and I still don't quite understand the colonial system. From what I've read on the paradox forums, the reason why Prussia don't get all of the colonial options, is because it's Prussia, and this should change later on, when Germany is formed. Is this also the reason why Prussia can't build any colonial buildings, in the F2 build mode?
When I try using tradepost or missionaries on, for instance, Samoa (where I currently have a colonial penetration of 10%), I'm told on the next turn that "the decision is not valid: the structure that is triggered by it would not be valid in this region".
According to the info on those two events, they only require that no other nation has a colony in the region, and that CP is 0-60 for missionaries and . However, I've tried playing both of those events successfully in other regions. So what's happening here? Are there any other, hidden requirements, that I don't know about?
Also, I still haven't been able to do a geographic expedition. I'm guessing that I need some sort of unit in the region, but the game hasn't informed of which kind I need. I tried sending an explorer units, but that didn't help (although that may have been due to a concurrent rebellion in the region).