Tapes and TSM

[Nazir]

Hi,

I have been working with TSM to make backups of my servers.
The TSM server is running on Windows NT.
The TSM makes backups and keep it in hard disk on server TSM, after sends
the data to tapes.
TSM is sending the data to tapes and the tapes become full. It is OK.
But TSM is not erasing the invalid data on the tapes (old files,etc..) !!!
What Can I do ?