Error Code -400

[Julie Anne McRae]

When Authenticating a connection in the PCCM_Demo Step 2: Connect to Amazon  I am getting 

MESSAGE: Failed to list buckets

CODE: -400

SOURCE: UseCredentials

I don't see a list of error messages in the documentation.  Is there one available?
I have double checked that i have the credentials entered correctly, and when i use dedicated S3 software  (S3 Browser by NetWDK Software)  I am able to connect and list buckets and upload files.
 I suspect this is a folder permissions thing, as when trying some other plug ins i was getting a http 403 error. 
Is it possible to know from this which permission needs to be given - so i know what to tell the folks at the "other end"