Purchase Order Print Problem

Hi All,

When the PO is created, output is not generated & gives red button saying no print relevant changes in the document.(ME 140)

This happens only when the dispatch time is 4 i.e. send immediately.

Output is created with no red button when the dispatch time is 3 i.e.send with application own transaction.

All the condition records & customization of output type are maintained correctly.

Why does the message output fail with transmission time-spot 4 (for sending immediately)

Checked sap notes , but not getting the answer.

Please respond asap,

Thanking you