Load next tape volume on device TAP01. (C G) (CPA4088)

OK,
 
I must be missing something here..
 
We have an 8mm tape unit (that "wonderful" IBM 9427.). Recently we
started going to a second tape. Unless I am missing something here I am
positive it automatically went to the second tape if one was loaded. I
KNOW it has been doing this.
 
Well last night/early this morning it issued the "Load next tape volume
on device TAP01. (C G)" to QSYSOPR and the second tape was loaded but
the backup terminated because it exceeded a preset run value we have in
Robot. It's like it did not bother to (try to) use the second tape. I
initially thought it might be the expiration date but this tape had been
initialized but never used ! And I know you can monitor in the backup CL
for the Load next tape volume on device TAP01. (C G) message (CPA4088)
but again, I have not had to do this in the past.
 
Any ideas ? (OH I miss the 3590 that I had at a previous job.)
 
Thanks,
 
Chuck