can you elaborate the the process a bit, this looks very brief:
When i am going to ME9F to take PO print, it is generating message successfully but new spool request is not getting generated hence unable to print.
I would usually expect that a new message is automatically created when you do the change. And this message is then processed from ME9F, precondition it has the same setup like your initial message for a new created PO.
But creating the message from ME9F seems not to be the right process for changes.
What message type do you want to print for the change, Message type NEU with the whole PO, or an extra message type for a change which has only the changes and not the complete PO?