Need help on Free Radius.

Hello All, I have an Active Directory on window 2k3 and I want to use the free radius on Linux machine for authenticating users domain. I tried to configure free radius with ntlm_auth for working auth but it not work. Although on free radius i can auth successful for domain user by command: ntlm_auth --domain=ABC --username=test ---> result: auth sucess (...), but on the auth client when i checked with the wrong name/pass it still showed message "auth sucess" after that this user/pass cannot login to device on domain. Can anybody help me on this and share me how to configure freeradius for authenticating domain uses? Thanks