[PO] Emergency PO - Error During AutoCreate

Emergency PO feature is only available in iProcurement. But, "we" did some customization on the core module to make use of this feature. In standard Oracle, emergency PO number is stored in EMERGENCY_PO_NUM field in PO_REQUISITION_HEADERS_ALL table. We have a custom form for emergency PR, which once submitted for approval, a emergency PO number will be generated and stored in EMERGENCY_PO_NUM field. DuringAutoCreate process, this PO number will be defaulted and greyed off (disabled field). This works fine.

Until 1 day, user reported an error message during AutoCreate, "This line cannot be put on the document because the emergency purchase order number for this line is different than the emergency purchase order number(s) for the other line(s).". Why?

The reported PR has 2 lines, line 1 already been AutoCreate to a PO. User tried to add another line onto the same PO, the above message appeared. During troubleshooting, I found out that the PO created was not a ePO, there is no PO field to identify (except the EMERGENCY_PO_NUM field at PR header), I confirmed this by verifying the ePO number, which we have customized. But, there was a value in EMERGENCY_PO_NUM field, and it is different from the PO number that was created earlier. Something wrong in our customization, which updated the EMERGENCY_PO_NUM field after the first AutoCreate. During the second AutoCreate, System is expecting the value in EMERGENCY_PO_NUM field to be equal to the PO number which was created earlier. To rectify this, I did date patch to set EMERGENCY_PO_NUM field to NULL.