short write on DLT 40G tape

[Benjamin Ash]

Hi,

We keep getting short writes when using our Overland DLT 8000 changer, 
and amanda:

<snip from a dump>
Output Size (meg) 16627.3 6514.9 10112.3
Original Size (meg) 31654.0 9046.7 22607.3
amanda.conf has :
tapetype DLT-8000-IV
define tapetype DLT8000-40 {
      comment "from amanda faq"
      length 37482 mbytes
      filemark 2362 kbytes
      speed 5482 kps
}
Anyone have any ideas why the amanda only writes 16gigs and then fails?

Thanks

-ben