You haven't given much detail about your application architecture, so i can only suggest a general answer. OAuth restricts which URLs can be referred to it. The list of permitted URLs is configured in the API console at https://code.google.com/apis/console. The URL is very fussy, so make sure you enter it exactly as it appears in the address bar.
As at Oct 2013, you can't use localhost. You have 2 choices.
- edit 127.0.0.1 = mydevserver.example.com into your /etc/hosts
- use a url shortener (eg. goo.gl) to create an alias to localhost
However, I believe that it is now possible to configure localhost in the Google api console.