Did you select a guy before typing allow dock? If not do it first and then type the command. Game needs to know who is the target which you want to accept, otherwise command won't work.
You can try re-mounting as well and try to give it to someone and then take it back.
If it doesn't help, reinstalling the game should be a fix. If isn't, I'm out of ideas and more experienced people will help you most likely.
Sometimes the simplest solutions are the best ~Ozu