The HTTP request is unauthorized with client authentication scheme 'Anonymou s'. The authentication header received from the server was 'NTLM'.

when testing a wcf web service, this error appears while it was working without any issue.
I had been searching for the answer for quite a while and none of them seems to fix my issue.
After reviewing my settings carefully, it appears that another settings in web.config is causing the problem. After I removed the section everything seems to be working again~