Richard, I posted responses to your msg, but I guess our email
doesn't send forwarded messages out.  Sorry.

Your checkin statement as written doesn't include the tape
volser, which might be just a typo in your message; our checkin
statement, similar to yours always brings good results:
  checkin libv 3590lib0 a00262 stat=scratch

I always keep a console session open at the time to observe
when ADSM requests that I insert a00262 into the priority slot so
I can respond:
  reply xxx                   where xxx is the task number

This works for us, and similarly for checkout where we have to
remove the tape from the priority slot.  --Diane