Problem - DLT IV tapes not being overwritten.

Environment:
-BE 9.1.1152 on a Netware 6.0 box.
-Using an HP Surestore 20/20 library with 2 DLT8000 drives.
-The library is setup using partition mgmt with partitions spanning 3 slots.
-Media server set to partial overwrite protection and overwrite recycable
media first.
-Policy - overwrite on Saturday, Append/overwrite if no appendable media
found Sunday-Friday.
-Media protection is set to overwrite - 1 hour, append - indefinate.
-Current data set contains only 68 GB.

ISSUE:
-The overwrite job completes normally.
-The next day's append job asks for next three tapes.
-Looking at the media stats shows:
media 1=19GB
media 2=0GB
media 3=-4GB.

-None of the media looks like they are being fully used (second media usually
not
used at all), but the job asks for new media each day.
- Have tried erasing the media (I know blank media is unappendable),
not erasing media (overwrite works, but append fails),
retiring and deleting media (same result).
- Have tried changing the media server to overwrite scatch media first (same
result).

I've run out of idaes and TIDs. Any suggestions? Any help is appreciated!

TIA
Gary C.