[arch-general] RAID 1 - Grub Problem / not finding stage1 file

[b1]

Hello alltogether

I am desperatly trying to get raid working. Currently I have Arch
installed on /dev/sda and I would like to make an RAID 1 Array out of it
(using /dev/sdb). I followed the guide from the wiki

(http://wiki.archlinux.org/index.php/Convert_a_single_drive_system_to_RAID)

and now I am stuck when I try to install grub on my newly created
raid1-drive (Chapter 3.6 in the Wiki). Everytime I do a
find /grub/stage1, grub only discovers the stage1 file on /dev/sda, but
not the one on my raid-drive (/dev/sdb). I have tried this normally and
from within the chroot environment, with no success. When I try to
install the bootloader manually via 

root(hd1,4)
setup(hd1)

grub gives the error 14: filesystem compatibility error.
I have absolutly no idea, what I can do now. /dev/sdb5 is a ext2
filesystem with type "Linux Raid Autodetect", containig all the
necessary files (mounting the partition and doing an ls shows the stage1
file).

Any help on what I should do now is greatly appreciated

Thanks

Benedikt