So me and F34RTEHR34PER are having a little problem. See, the plot owner typed the command /plot promote {player_name} but the command is probably still a little bit glitchy and it continues to say "You must be plot moderator to set commands."                                            

If you type /plot info (not /plotme) you can see a list of plot moderators. If you're not on the list, the plot owner hasn't promoted you.