title: PlusSampleActivity an internal error occurred
body: <p>When I tried to run the PlusSampleActivity from the google plus SDK, I cannot sign in with google+ sign in button. It shows a toast "an internal error occurred". </p>
  
  <p>I am pretty sure my package name is correct and SHA1 is correct too.</p>
  
  <p>The keystore I used is correct. I am pretty sure, because I use that keystore to register facebook app, and it works.</p>