I don't know if this is your problem, but we had fits with the DLT7000
drives shipped with a 9714.  It turns out that the drives were seriously
(like two years) downlevel in microcode.  Even replacment drives off the
shelf were downlevel.  Get STK to check this.  We've had no problems with
the 9714/DLT7000 combo since.

>Subject: Tape storage devices DLT & Magstar
>    Hello ADSM'ers I was courious to see just what type of problems people
>     who support ADSM and the storage of data on either DLT or Magstar's
>     are encountering. I recently moved from 3490 to DLT 7000 and noticed
>     that while it is nice having the STK 9710 mount tapes it takes almost
>     as much monitoring as having operations mount tapes. With tapes not
>     unloading from drives sometimes and the sense errors when a drive is
>     busy and another tape can not be mounted in it. Our company is looking
>     at having a total solution for disk array and pc's and a single large
>     unix server all backed up with ADSM and I want the best hand's free
....deleted....

Dan Hale