adding drive to raidz1

[Randy Bush]

so, i made the jet-lagged mistake of saying

    # zpool add tank ad7s1

and got the following

    # zpool status
      pool: tank
     state: ONLINE
     scrub: none requested
    config:

	    NAME        STATE     READ WRITE CKSUM
	    tank        ONLINE       0     0     0
	      raidz1    ONLINE       0     0     0
		ad4s3   ONLINE       0     0     0
		ad5s3   ONLINE       0     0     0
		ad6s1   ONLINE       0     0     0
	      ad7s1     ONLINE       0     0     0

when i wanted to add it to the raidz1.

    # zpool remove tank ad7s1
    cannot remove ad7s1: only inactive hot spares or cache devices can be removed
    # zpool offline tank ad7s1
    cannot offline ad7s1: no valid replicas

how do i pry it off of the pool and stick it into the raidz1?

thanks

randy