"Clear text password not available"

["Flavio Silvestrone" <drascii@gmail.com>]

Hello list,
For me it's the first time with freeradius; i try to find a solution or a way to solve my problem but i have not found anything.
I have this message on the log of the freeradius server when a wireless client try to estabilish a pppoe session.

Auth: Login incorrect (rlm_chap: Clear text password not available): [flavio/<CHAP-Password>] (from client Erri port 1511 cli 00:35:00:04:60:99)

The message is clear but i don't know where to solve.
The configuration is:
- two wireless client with pppoe profile
- one wireless Access Point
- one freeradius server

If i enable the same pppoe profile (user: flavio, password: flavio) on the Access Point all work fine; When i disable the profile on the Access Point and i configure the radius client on the Access Point i have the problem
This is the configuration on the file /etc/raddb/users for the user "flavio" :

       Service-Type = Framed-User,
       Framed-Protocol = PPP,
       Framed-IP-Address = 
10.1.1.8,
       Framed-IP-Netmask = 255.255.255.0,
       Framed-Routing = Broadcast-Listen,
#       Framed-Filter-Id = "std.ppp",
       Framed-MTU = 1500,
#       Framed-Compression = Van-Jacobsen-TCP-IP

Any idea to find out the prob ?
Than's a lot
Flavio