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.