I was playing on warlord level the other night and I was behind on tech. I'd gotten into a few major wars and simply fell behind. I did have a lot of extra gold and was paying a premium to Babylonia in order to catch up. Americans were also ahead of me and they were selling tech cheaper. One turn I get a pop up window that says Babylon is building Leonardo's Shop, then a pop up that says America's building Leonardo's Shop. So I go to the Americans to trade for invention. They didn't have it! I thought I imagined it, so I keep playing and soon enough Babylon and America are building Smith's Trading Post. So I go to the Americans and once again they don't have Economics. Is this a glitch? I'm only one or two tech behind them so I don't think it's because I don't have prerequisite tech. Weird huh? "do or do not, there is no try."