Assuming you really have 111 images on that tape, have you tried it
from the command line?
mt -f /dev/nst0 rewind
mt -f /dev/nst0 fsf 111

If mt fails, it isn't an amanda problem.  If fsf 111 fails, try an
mt -f /dev/nst0 fsf 1 and see if that works. If '1' works but '111'
fails, you may not have 111 images on that tape.

Frank