Ionic Push-tutorial and app

Hi Ionites. I downloaded the Ionic Push_tutorial Git repo and followed the guidelines without obvious ommissions. Here is the problem: the app works up to a point on an Android device and responds to ionic serve --lab. When I add gcm_id: ‘my_id’ it in app.js does neither. In fact it gives a blank screen after the splash page. When I \ comment it, it displays. Clearly it does not permit user registration. I have rechecked all the steps on the Google developer interface a few times. Please assist if you can.