How can i fix "your computer isn't setup to use restricted permissions in office 2011 (mac)

Hi

please help me here, i'm working on a mac and in word 2011 and when i try to click file then restrict permissions i get the error message "your computer isn't set up to use restricted permissions. open rights protected document or email message from someone within your organization to set it up.

I really would like to know how i can fix this. Please help.

I tested with Office for Mac Standard 2011 and Office for Mac Standard 2011 (The version provided by Office 365).