curios problems creating a new Raid5

Really don't know what i've done, but it's solved!
Steps:
1. Stupid md0-derivates showed up
2. Deleted the filesystem, deleted raid (and derivates also were gone), deleted smb share, deleted old entries of mdadm.conf
3. Shredded all devices (secure via webgui button)
4. Recreated Raid --> derivates showed up again!
5. Created new filesystem
6. configured fstab (mounting filesystem in special path)
7. reboot
8. derivates are gone!!!!