Set membership not show ranks

Hi everybody,
when i try to Set Membership to users it show an empty square. I'm not sure if i had disabled something. How can i fix it?
I have more question, i added an user as Operator with "Accounts" Plug in. What is the differences from operator and administrator? He as operator can do anything but maybe not all: for example he can't Set a Badge. Why?
Thank you for replies! :)