When i add images, the thumbs does not shows and then i can't change the chmod or download the thumbs with ftp client. Where is the problem?
hard to say without a link. It might help as well to post a test user account (non-admin), enable "debug mode" in coppermine config for everyone(with notices display disabled unless they mean anything to you) and upload method set to "Single file uploads only" for all groups in groups control panel.
Joachim