GWT rpc not works without internet connection in local machine, but with internet it works

I implemented an rpc call. It works on local machine but does not work without internet connection (like turning off the wifi connecion or LAN connection), although internet is not necessary for the simple call. I am not using google app engine. In the client side, it开发者_运维问答 returns onfailure method "rpc....statuscode:0", and no other errors. Why? Any ideas?

i uninstalled my xmpp (apache server) then it woked.the reason is now clear xmpp was holding the localhost..