Obviously you have single player commands installed, but no big this only means one feature of the mod is not working same here I always got the same message lolz.
same some 1 help US :(
Make sure the plugin isn't outdated, and check what your console says.
There is an option on the downloaded version that says "play offline" click that.
You have to install the plugin.
Try clicking options in the log in menu and do "Force Update". If that doesnt work, try going into your files, search "%appdata% and delete your .minecraft folder. Then go to minecraft again and it should re-install all the updates.
Have you bought the game? Platnium mean that you have purchessed it. If you haven't, then you will need to in order for it to say 'Platnium'.
Update your minecraft.
Do a force update.
You plug in your USB where it says USB plugin. Then everything else is self explanatory.
the demo? you play it like you play minecraft just do what it says
From Minecraft Wiki... it says this Wednesday (October 24th 2012) but I am still not sure.
she doesnt want to do it or doesnt like what you are telling her...and doesnt want to tell you or you to know