Sometimes, no matter how many times I drag/drop someone from the "garrison" to a place, they won't go there. It's happened with converted natives, elder statesmen, etc. They won't farm, they won't go to the town hall, they won't chop wood, they won't make cigars, and on and on and on. Every now and then, i drag and drop a unit within a town and it won't do anything. It just stays in the garrison. I move them to another town, and they work just fine.