Thanks, turns out to be what you have mentioned above Alan " shared secret"
another issue in my newly installed FreeRADIUS Version 3.0.4, i do not see detail file is created although I have enabled in sites-enabled/default file. This server is just act as an proxy i.e forwards realms to remote home servers.
I copied from my version 2 radius server proxy.conf and clients.conf , doing radiusd -XC tell me OK. Off course all the server ip and port listen are moved to sites-enabled/default file. are there any specific change that I have to make in version 3.0.4 just act radius server as an proxy ?