Make sure you've actually added a NAS in as a type Radius (VPN3000), otherwise none of the attributes will show up even though you've checked the box (although to be able to check the box you have to have added a NAS, so I'll assume you've done this :-) ).
It shows up fine on my system here, just tested it. It could be the CSAdmin service on your system has gotten screwed up, it happens sometimes. CSAdmin is the service that controls the GUI. go under Control Panel - Services and stop/start CSAdmin and see if that fixes it.
Note: don't go under System Config - Service Control within the GUI and restart the services that way, cause that restarts all the services EXCEPT CSAdmin (otherwise you'd lose your browser/GUI connection).
