Did you clear the superblocks on both drives, and did you convert all partitions on the second drive to 0xfd?
Double check if your sequence was identical to the one described here:
http://www200.pair.com/mecham/raid/r...aded-etch.html. If not, go back to a point in the instruction list where you know you had a condiguration which worked as expected. Then redo your actions.
I can assure you it works in Debian, followed this list last week also on a sda/sdb configuration.
jlinkels