Trying to setup RAID

Hi,

I am following the instructions here:
http://macprojournal.com/partitions.html

to setup raid.

I have got the three volumes, all labelled correctly, on each disk.
When I hit the RAID button I can add all the partitions apart from any that are on the disk in bay 1.

I could understand this if you couldnt boot off of a raid, but apparently you can.

Any ideas please? Not getting this to work means I am going to have to go to bed before I get my new mac working

Thanks,
Simon.

The only differance I can see is if I select the disk, for the one in bay1 it says the partition scheme is Master Boot Record.
For all the others it says GUID partition table; cannot see how to change Bay1 to this.