mdadm create keeps giving error about existing file system

While trying to create a software raid set:
with the following command:
mdadm --create etc etc etc
The correct syntax.

I get the following error:
"/dev/blah appears to contain an ext2fs file system"

I have tried the following methods to resolve the error:
1.) deleting the partition,
then remaking the partiton with a different partition type.
including the compulsory reboots.

2.) clearing the superblock.
mdadm --zero-superblock /dev/partition

Any ideas?
Just dd the parition?

-- 
Luke Computer Science System Administrator
Security Administrator,College of Engineering
Montana State University-Bozeman,Montana