I duplicated a theme and it was copied with chmod 777 all over. Now when I try to change the permissions with my ftp client it's not permitted. I also tried by cpanel. I'm wondering if this is a server issue. But I never had problems to change permissions before.
Thank you for advise!
More likely it only affects folders that Zenphoto has created which would include (but not be limited to) duplicated theme folders. Anyway, as I said, Zenphoto does not manage security on your server. If somehting is not working correctly it is a server configuration issue.