Can you please help me understand how a purchase requisition (PR) works in a maintenance work order?

I’m facing an issue: I raised a purchase requisition (PR) for operation sequence 10, but a purchase order (PO) was not created or received. However, I was still able to execute the work order.

Could you please explain the complete process of how purchase requisitions are handled in a maintenance work order?

From my understanding:

• A PR is created for an operation sequence with Destination Type set as Work Order.
• Then, a PO is expected to be created based on the PR.
• Once the PO is received, only then should the work order execution be allowed.

However, in my case, execution was allowed even though the PO was not received.