radius log not recording some NAS client IP

[iamjimme]

hello all
I am running 2.1.1-7.10.1 freeradius server on SLES.
The radius server is attached to a ldap server for authentication.
Right now everything is running pretty smoothly.

Basic log is being written to the default log location 
(/var/log/radius/raidus.log), but I noticed sometimes, some NAS client 
IP is not logged. I am sure the this info is available in the debug 
mode. Afterall the clients.conf is checking the ip come in.
for example, a normal record would look like this:
<Date> : Auth: Login OK: [james13] (from client able322 port 0 cli 
10.22.31.51)
but an incorrect record would look like this
<Date> : Auth: Login OK: [james13] (from client able322 port 0)

Has anyone seen this kind of problem, or can someone advice me on how to 
alter to log manually to record this piece of info.

Thanks for your help