I'm implementing a WiFi AAA server with PEAP(mschapv2) method over radius stack. and I test AAA server through PC with windows xp, vista, and also through iphone and serveral kind of smart phones. It succeed with iphone and smart phones , they can access internet after authenticated by my AAA server. But the problem is windows client. AAA server authenticated client successfully and answered with encrypted auth_string (rfc2759 : Microsoft PPP CHAP Extensions, Version 2). but the client (windows pc) does not answer. 1. I confirmed the success string (S=40byte string) is correct. 2. encryption key is also used at the previous step(challenge, response) and successfully passed. 3. then what could be the problem? if connect through intel proset wireless connection utility, it also succeed in windows xp. HELP PLEASE~~