Had something just like this recently. When the command disk show -n doesn't display any unowned disks but when you run the disk show -a and you see your disks present.
You may only need to put them into the "unowned" mode.
Try this command: disk assign <disk id number> -s unowned -f.
Then run your disk show -n and see if it is now unowned. If it is, then do this command to all the drives you are trying to take ownership of.
When done run: disk assign all.
This should now add the drives to your Netapp as owned drives.
Keep in mind that the disk.auto_assign must be on.
To view this just type options disk and look for disk.auto_assign. If it is set to "off" you can turn it on by typing options disk.auto_assign on
Hope this helps.
Best of luck.