I was playing ming for the second time on iron man mode, when I try to conquer buthan province from the indian kingdoms. It doesn't work! the first time I clicked on buthan to take it and then I vassalized them. (yes i actually clicked on the conquer button before I vassalized them) The second time I played ming and tried to conquer buthan, it didn't work. This time I made the kingdom become my triburtary state (and yes I did click on the province I wanted to take before i made them my tributary) sry for my bad English