Edit button dissapear

hi everyone
i work with webmethods 7.1.2 and i have this problem.
i created a public folder and put a inbox, in this portlet dissapear the edit button that allow add new columns, but in webmethod 7.1, exist this button.
Edit button only appear when i am login as Administrator or when add the inbox pushing the “Add custom page”, in the version 7.1.2.

how i can solved this???

thanks in advanced
Rodolfo