[isf-wifidog] Client gets blank page when trying to login to RADIUS based network

[Mark Dammer]

I am trying to get Wifidog to cooperate with freeradius. While 
non-radius based logins to Wifidog work well, the clients get just a 
blank page once they have choosen the RADIUS based network and entered 
their login credentials.
My guess is the problem lies where Apache throws a fatal PHP error at me:

[Tue Jan 18 11:52:31 2011] [error] [client 172.16.15.126] PHP Notice:  
Use of undefined constant en_US - assumed 'en_US' in 
/var/www/wifidog-auth/wifidog/config.php on line 160, referer: 
http://172.16.1.111/wifidog-auth/wifidog/login/?gw_address=172.16.15.1&gw_port=2060&gw_id=wifitest&url=http%3A//start.ubuntu.com/10.04/Ixquick%2520HTTPS%2520-%2520UK/
[Tue Jan 18 11:52:31 2011] [error] [client 172.16.15.126] PHP Fatal 
error:  Call to a member function getId() on a non-object in 
/var/www/wifidog-auth/wifidog/classes/User.php on line 133, referer: 
http://172.16.1.111/wifidog-auth/wifidog/login/?gw_address=172.16.15.1&gw_port=2060&gw_id=wifitest&url=http%3A//start.ubuntu.com/10.04/Ixquick%2520HTTPS%2520-%2520UK/
[Tue Jan 18 11:52:34 2011] [error] [client 172.16.1.15] PHP Notice:  Use 
of undefined constant en_US - assumed 'en_US' in 
/var/www/wifidog-auth/wifidog/config.php on line 160
[Tue Jan 18 11:52:54 2011] [error] [client 172.16.1.15] PHP Notice:  Use 
of undefined constant en_US - assumed 'en_US' in 
/var/www/wifidog-auth/wifidog/config.php on line 160

The RADIUS server is not receiving any connection attempts.
These are the Authenticator parameters: 
'radiustest','172.16.1.111',1812,1813,'xxxx','CHAP_MD5'
As I said before: If I choose a non-radius based network I can login to 
Wifidog without problems.

thanks for any help, Mark