Fiddler is a great tool for tracking/debugging your network traffics. But sometimes it doesn't work with google chrome.
Turns out that some of my google extensions, "Unblock Youku" and "Proxy SwitchySharp", will interfere with chrome's proxy settings, causing fiddler not working. Disabling them makes fiddler works again.
some other plugins like "FoxyProxy" and "SwitchySharp", etc. may have similar effects.