How changing volume (in stand-alone mode) ?

[clocatel]

With a NT server, using 1 dlt 8000, how can I change the volume ? (TSM 4.1)

1. I create a volume (labeled TAPE1)
2. I backup files
3. I dismount this volume
3. I create a new volume, (cmd : DEFINE VOLUME ...) ex : TAPE2
4. When I backup some files, TAPE1 is still wanted. Why not TAPE2 ???

Please, help me !!!!