System: Group manager–Privileges list, FreeRADIUS: Users page, not listed

[sarthor]

HI, I search forum, but was not able to get appropriate answer,

I am using freeradius, captive portal. Created group name, "opreator" in system–user manager--group-manager, I want to allow only one page to access to this group, and the page is ...Service--FreeRADIUS: Users, but the page is not listed in System--User manager--Group Manager--add privileges, How can I allow group that can access only this page.
waiting for replay.. Thanks in Advance.