Reauthenticate Every minute

[Mutheu]

My Setup:

--> FreeRADIUS:  Version 2.1.12, for host i386-redhat-linux-gnu, built on Oct3 2011 at 21:39:42 
--> Mysql: Server version: 5.1.51 Source distribution
--> NAS: pfSense 2.0.1 release 


My Query:
I am a bit new to freeradius and I am trying to create a setup where an active session is
re-authenticated everyminute and a user is kicked if no enough credit.


More Details:
Using 'norestcounter' with mysql works very well without the above.
Now I would like to implement this idea : http://computing-tips.net/M0n0wall_Captive_Portal_Logout_URL/#onlinestore).

NAS supports a feature for "reauthentication every minute".


The problem is that, if I turn it on, freeradius responds:

Sending delayed reject for request 2
Sending Access-Reject of id 234 to 10.250.78.200 port 64881
        Reply-Message := "\r\nYou are already logged in - access denied\r\n\n"

Activated the option for ensuring no 'simoultenious use' via mysql.


What am I missing in the freeradius config?

Mutheu