Problem in Asterisk

hi all…i just download and install X-Lite Client on Win XP and I use Asterisk server on my Linux Fedora Core 4… I have a problem when i want to register…got a message like this

Dec 22 19:47:07 NOTICE[14388]: chan_sip.c:10817 handle_request_register: Registration from ‘Zaky sip:zeronature@’ failed for ‘’ - Username/auth name mismatch

pls help me on this error message…thank you

errr … it means your authentication details don’t match ! make sure the details you have in sip.conf for your softphone extension match the ones you’re entering in the X-Lite setup.

if you’re still stuck, post the relevant bit of sip.conf here.