mpd vpn + freeradius problem

[王岩]

Hi, I want to use freeradius1.0.4 to auth and acct mpd_3.18_2 PPTP VPN (on FreeBSD).
But I have a problem.
In the log file, it displayed the following messages:
"
Jul 13 10:32:53 vpn mpd: [pptp1] RADIUS: using /usr/local/etc/raddb/radiusd.conf
Jul 13 10:32:53 vpn mpd: [pptp1] RADIUS: rad_config: /usr/local/etc/raddb/radiusd.conf:23: invalid timeout
Jul 13 10:32:53 vpn mpd: [pptp1] CHAP: sending FAILURE
Jul 13 10:32:53 vpn mpd: [pptp1] LCP: authorization failed
"

I check radiusd.conf:23 .
"
#       The per-request variables are of the form %{Attribute-Name}, and
#       are taken from the values of the attribute in the incoming
#       request.  See 'doc/variables.txt' for more information.

prefix = /usr/local   <----------------------line 23
exec_prefix = ${prefix}
sysconfdir = ${prefix}/etc
localstatedir = ${prefix}/var
"

Anyone can tell me what it means and how can I resolve it? 
Thanks

wangyan