SoapUI global proxy testings doesn't work when executing tes

I have created a web test project using the SoapUi GUI (free version). I need a proxy to connect to the Internet. Therefore, I have set the proxy host and port in File->Preferences->Proxy Settings and made sure that it is enabled. The proxy is correct, because I can see the "soapUi Starter Page" properly and I can create SOAP project via WSDL successfully. But when I execute the test cases, it always shows the unknow host. It seems that the proxy settings doesn't take effect.

Does anyone can help? I'm testing this public web service: http://www.webxml.com.cn/WebServices/We ... rvice.asmx

Is it a bug?

Thanks