S3cmd errors on Mac OS X

I try to use s3cmd-1.5.2 on Mac OS X 10.8.

The initial sync works fine.

The second generate errors ERROR: S3 error: None and keep re uploading most files…

In debug I see that when s3cmd is doing

DEBUG: Sending request method_string=‘PUT’, …

It generate an InvalidRequest and

DEBUG: ConnMan.put(): connection put back to pool
ERROR: S3 error: None
WARNING: Unable to remote copy files …

Any idea what is wrong ?

For information I could not fix the problem so I switched to use boto and specifically boto-rsync. It was easy to install and I have what I want : a one liner to backup any folder on my machine to DreamObjects… Still I use s3cmd if I need to create a bucket or delete it.