Native 2003 backup won’t overwrite tapes!

Using some new and some previously used tapes: tried using the wizard to set up a job to overwrite, also instead manually created a script; these just fail with either “no storage media specified” or “cannot find …”

Have to run manually and then answer couple of questions about overwriting existing backups. I must be missing something in the switches but cannot find them!

Tried with “Remote Storage” service off and on, not sure if that will make a difference but with it on it hangs.