Note from Support -
Confirm that the tapes you are using originate from a trusted seller. We have had reports of some tapes obtained through marketplace vendors (ex: Amazon, Ebay, NewEgg) being damaged, used or non functional. We love the convenience of marketplace sellers for all sorts of products, but tape is a highly specialized field and nothing sucks more than spending over $100 on something that does not work. You are much safer using people with experience in that field. We sell tapes on and can verify their authenticity.

If error code 6 is present and ejecting the tape clears the 6 error code, the media is the likely culprit.

If you are certain your tape is functional, but still see error code 6 or 7, contact MagStor support.