I was looking at my game-log, and I saw something very strange. Yesterday happened to somebody 4 times in row:
Some player selected an action, but this action was refused by server, because the server "thought", that this action was ALREADY used.
The possible reason could be, that you used an action, but it for some reason did NOT disappear from the list afterwards. And when you tried to use it again, it just didn't work anymore. I really don't understand how could this happen, can somebody please confirm that it happened to him?