Hi Garry,
let me guess the situation you have,
The old tapes you are using, were they used in a DLT4000, DLT7000 or a DLT8000 tape drive? I am thinking DLT4000.
If so, is the new tape drive you are trying to format these tapes on a VS80 drive?
If it is, you won't be able to erase the tapes, as the VS80 doesn't support writing to tapes written to by a DLT4000.
The only way to use those tapes again is to get them professionally erased.
Veritas have a link about it:-
http://seer.support.veritas.com/docs/245145.htm
Harry