Modified and tested the screen scrape extracting the data chunk by chunk, limit the extracting by hundred, this is to see if the screen scrape is OK and if there are problems in the data will see if what SKU is causing the problem. As per checking, when executed the screen scrape with a query extraction limited to first 500 rows only, the PO creation is successful, meaning the screen scrape is working, thus the suspected cause is the data. Modified and tested the screen scrape query extracting limited to 500 to 1000 SKUs, all the processed is successful and the PO is created, but when limited it into 1100, the PO is not created, the SKUs for the first invoice to be created is 1068. Modifed the screen scrape again, and add the displaying of the SKUs count per invoice and the SKU that is being processed, to see where the processed stop, tested the changes, and the screen display the count and the SKUs that is being processed with a extraction limited 1050 rows,  as per testing, the error is encountered again, modified the query again and limit it to 1010 to 1020, and all is successful, listed the SKU that is processed successfully. The checking will continue tomorrow but found out that one or more SKU is causing problems from the remaining 48 SKUs.