trying to erase HD and....

[edgarbc1]

disk utility says error, cannot unmount disk.
im booted into another disk, separate from the one Im trying to erase.
the HD is on a owc data doubler mount in the optical drive bay for a MBP.
ive repaired permissions, verified disk and
rebooted to insure the drive is not active by some other application.

im in ML... i have an external SL HD which im going to try next and erase that internal HD
any other tips would be welcome.

thanks
E

[Chakravartin]

Safe boot.

[edgarbc1]

the SL HD boot let me erase that disk
thanks tho