Below was my problem solved:
http://social.msdn.microsoft.com/Forums/zh/wcf/thread/02ce9fb9-6f67-45ec-9668-2dcd2317aab0
If you are behind a firewall, you need to force Visual Studio to use the system proxy settings, which can be done by manipulating the devenv.exe.config file.
Open it in Visual Studio and change the section as shown below:
<system.net> <defaultProxy useDefaultCredentials="true" enabled="true"> <proxy usesystemdefault="True" proxyaddress="http://yourproxyserver:port" bypassonlocal="False"/> </defaultProxy> <settings> <servicePointManager expect100Continue="false" /> <ipv6 enabled="true"/> </settings> </system.net>
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