Android GCM registration / device id for push notification is getting changed everytime -

i used code gcm registration id. (earlier)

// make sure device has proper dependencies.         gcmregistrar.checkdevice(this);          // make sure manifest set - comment out line         // while developing app, uncomment when it's ready.         gcmregistrar.checkmanifest(this);    //        registerreceiver(mhandlemessagereceiver, new intentfilter( //                commonutilities.display_message_action));          // gcm registration id         final string regid = gcmregistrar.getregistrationid(this);          // check if regid presents         if (regid.equals("")) {             // registration not present, register gcm                        gcmregistrar.register(this, commonutilities.sender_id);           } else {              appsharedpreferences.savedeviceidpreference(ctx, regid);              // device registered on gcm             if (gcmregistrar.isregisteredonserver(this)) {                 // skips registration.                  //                toast.maketext(getapplicationcontext(), "already registered gcm", toast.length_long).show();             } else {                 // try register again, not in ui thread.                 // it's necessary cancel thread ondestroy(),                 // hence use of asynctask instead of raw thread.                 final context context = this;                 mregistertask = new asynctask<void, void, void>() {                      @override                     protected void doinbackground(void... params) {                         // register on our server                         // on server creates new user                         serverutilities.register(context, regid);                         return null;                     }                      @override                     protected void onpostexecute(void result) {                         mregistertask = null;                     }                  };                 mregistertask.execute(null, null, null);             }         } 

but, shockingly, seems change everytime on execution, for same device , same application. please let me know possible reason of that.

edited

modified gcm newer version

gcm = googlecloudmessaging.getinstance(this); new registerbackground().execute(); 

followed this tutorial.

but, still same behaviour, i.e, getting new reg id on every install.