Error 403

Hi,
I’ve followed the instructions but the agenda is not working. I’ve got the error 403 message (http://screencast.com/t/3izVOqpIkq4).
I created the API Key and the OAuth ID ( http://screencast.com/t/vr43jJQOffMb ) and my agenda is public (http://screencast.com/t/Ul1sP5oebwO ), so I really don’t understand what’s wrong.
I’ve used your plugin before and it was working with the same theme.

Could you please advice?
Thanks for your support.
Regards