Need information about proxying

[Vishwanath Srikant Pattanshetti]

Hello 
I am trying to using Freeradius1.1.0 I want to use it as a proxy to an
external RADIUS server. 

In such a setup, if my external server is not up, and if I proxy a
request to it, then I get back a access-reject, from my proxy radius
server. Also 
If the username/password mismatch on external server then also I get a
access-reject. Is there a way I can differentiate between these two? 

I mean is there a way I tell if the external RADIUS server is down OR 
Authentication at external RADIUS server has failed?

Please please help in this regard.
-Vishwa.