I had tried to use the Google Map Sample Code before which was provided in Google_Play_SERVICE/SAMPLE by using all the available options and it showed the below
Please use the Browser key when you download and run the sample project from the internet. Android key will not work in that case and will give this error.
"Could not contact to server. Authorization Failed"
Go to your API Console and get your browser key
Thanks
Let me know if you have any queries regarding Google Maps Api V2