Google_AuthException : invalid_grant-Collection of common programming errors

I’m trying to setup the config.php with my values but I get this fatal error:

Fatal error: Uncaught exception ‘Google_AuthException’ with message ‘Error fetching OAuth2 access token, message: ‘invalid_grant’.

I entered the client ID, secret, simple API key, location and sqlite database as the documentation says here: https://developers.google.com/glass/quickstart/php

Any idea of what I’m doing wrong?

Thanks in advance!