android - App Engine Backend with Google Cloud Messaging connection fails building release version with proguard -

i have android app using gcm , app backend in google app engine. works fine in debug mode. in intentservice "registrationintentservice" token calling

instanceid instanceid = instanceid.getinstance(this);           string token = instanceid.gettoken(sender_id,                         googlecloudmessaging.instance_id_scope, null); sendregistrationtoserver(token);//send app engine 

and pass app engine backend with

private void sendregistrationtoserver(string token) {     //     if (regservice == null) {         registration.builder builder = new registration.builder(androidhttp.newcompatibletransport(), new androidjsonfactory(), null)                 .setrooturl("https://android-app-backend.appspot.com/_ah/api/");                //where android-app-backend corresponds own project id          regservice = builder.build();     }      try {         regservice.register(token).execute();     } catch (ioexception e) {         e.printstacktrace();     } } 

it works fine if generate signed apk disabling proguard

(minifyenabled false) 

but if generate apk enabling proguard can token(registration id),but cannot store in cloud. android application log tells me

d/libc﹕ forward dns query netd(h=*****************.appspot.com s=^) w/system.err   com.google.api.client.googleapis.json.googlejsonresponseexception: 404 not found w/system.err﹕ not found w/system.err﹕ @  com.google.api.client.googleapis.services.json.abstractgooglejsonclientrequest.newexceptiononerror(unknown source) w/system.err﹕ @ com.google.api.client.googleapis.services.json.abstractgooglejsonclientrequest.newexceptiononerror(unknown source) w/system.err﹕ @ com.google.api.client.googleapis.services.abstractgoogleclientrequest$1.interceptresponse(unknown source) w/system.err﹕ @ com.google.api.client.http.httprequest.execute(unknown source) w/system.err﹕ @ com.google.api.client.googleapis.services.abstractgoogleclientrequest.executeunparsed(unknown source) w/system.err﹕ @ com.google.api.client.googleapis.services.abstractgoogleclientrequest.executeunparsed(unknown source) w/system.err﹕ @ com.google.api.client.googleapis.services.abstractgoogleclientrequest.execute(unknown source) w/system.err﹕ @ com.example.android.registrationintentservice.a(unknown source) w/system.err﹕ @ com.example.android.registrationintentservice.onhandleintent(unknown source) w/system.err﹕ @ android.app.intentservice$servicehandler.handlemessage(intentservice.java:65) w/system.err﹕ @ android.os.handler.dispatchmessage(handler.java:99) w/system.err﹕ @ android.os.looper.loop(looper.java:137) w/system.err﹕ @ android.os.handlerthread.run(handlerthread.java:60) 

my proguard file default file 'proguard-android.txt'.

how can fix issue?