"Not a valid command"?

[LizzieS]

I'm trying to figure out how KidMUD works, and one of the things I've been having trouble with is entrances and exits. According to Perry's guide on the main site, to enter and exit a room you just type in one of the name of the "obvious exits". So I've been trying that, and often I'll type in one of the names and it'll say "that is not a valid command". Am I doing something wrong? Can one of the KidMUD geniuses help me?