AutoCreate AMount based Req into PO

Hi we are looking into automating Requisitions for specific Categories into Purchase Orders. We created Approved Supplier Lists (ASL) for specific Categories and assigned Contract Purchase Agreement in the Attribute section. Then we created a Sourcing Rule and Assignment Sets. We were successful in having Requisitions for Item Types "Goods billed by quantity" and "Services billed by quantity" automatically created in to Purchase Orders. We have not been successful in getting requisitions for Item Type "Goods or services billed by amount" to get processed by the AutoCreate Po program. We have Profile Option PO: Automatic Document Sourcing set to No