I installed the Force.com for Amazon Web Services app into my Developer org and set up my S3 credentials, carefully following the instructions on this page:
However, I consistently get this message, e.g. when I click on the "S3 Samples" tab:
Web service callout failed: WebService returned a SOAP Fault: Access Denied faultcode=soapenv:Client.AccessDenied faultactor=
Is there something I have missed in the setup that would cause this error?