bam-restore can not read its own backups

Hello

I just installed a new Drupal 7 website, added Backup and Migrate and created a full site backup.

Restoring does not work, the command
bam-restore archive ...
always says:

Files were not restored because the archive did not seem to contain a files directory or was in a format that Backup and Migrate couldn't read

I've tested "No Compression", Zip, GZip and BZip.

And this blocker is strange, too:

Backup and Migrate cannot restore the php code of the site for security reasons. You will have to copy the code to the server by hand if you wish to restore the full site.

because:

1. I started "bam-restore archive ..." from the shell
2. I try to restore a backup which is on the local server but (of course) not in the Drupal tree.
3. This protection "for security reasons" is really strange, because if a hacker has access to Backup and Migrate then it's too late anyway. Therefore, this disabled restore full site function provides no additional security but blocks the Administrator
4. It would be great to replace this warning by an useful manual what "You will have to copy the code to the server by hand if you wish to restore the full site.". Or does it mean that I really have to manually start "unzip ..."?. This would be really bad, because my users know that a restore will overwrite everything, but the do not know bash.

Kind regards and thank you very much for your great work!!
Tom