Can't send the following request to your server

hi , 
how to debug issue with no response from Redpin server.

i have been try ,download or re-builder project with Redpin redpin.jar.
and Android app (Redpin) ,it always Redpin server is not reachable. 

then ,i use netcat tools to send request 
{"action":"setMap","data":{"mapName":"YOUR MAP NAME","mapURL":"http://your-url.org/..."}} 
the Redpin server return  tcp server:empty