Access to role categories in the USer management module

I'm looking for what the admin role which needs to be added in user management to user for him to be able to update the 'role category'. I currently need to create a new category but it returns an error message somehow that i don't have enough privileges... where i'm actually assigned to the same admin role as the sysadmin user. Thk to let me know if any of you is having by chance some tips. It would be very appreciated.