Is it possible to flush and dump to the same tape?

I'd like to use a script something like this:

# turn on hardware compression
/usr/local/bin/vxaTool /dev/st0 -C 1
# flush any old backups
/usr/sbin/amflush -f -b SeinerHome
# dump new backups
/usr/sbin/amdump SeinerHome
# verify backups
/usr/sbin/amverify SeinerHome
# and eject tape
/usr/local/bin/vxaTool /dev/st0 -u

but amanda fails to dump with the following message:

*** A TAPE ERROR OCCURRED: [cannot overwrite active tape SeinerHome06].

I am trying to make this as idiot proof as possible, so that we only have to 
stick a new tape in the drive, and everything else will be handled 
automagically.

--Yan