Don't know how you have it set up, but check:
1) Make sure each memory channel is Set for LTR, if it is
NOT set to LTR the scanner does not know which decoding scheme to use. If you try to enter the ID, it
WILL give you an INVALID ID value.
2) Use this link for the easy to read manual for the Pro-97:
http://myweb.cableone.net/marksscanners/97/97.html
Hope I helped you my friend,
Merry Christmas