create PO without Manual intervention

Hi Gurus,

I have below requirement :

Requirement : As soon as Requisition is APPROVED, a Purchase order should get created in "APPROVED" Status.

Action taken :
1- ASL setup done.
2- Sourcing Rule setup Done .
3- Assignment set -Done as per MRP Default sourcing rule assignment set.
4 - In "CREATEPO workflow"  following attributes are set to :
     AUTOCREATE_DOC--"Y"
     AUTO_APPROVE_DOC..."N"  also tried with "Y"
     IS Workflow Create the RELEASE...."Y"

5- IN "Requisition Approval"  Workflow ,following attributes are set to:
     Send PO Autocreation to Background’ ..."N"

After setting the above,I have created a requistion then Ran requests "Requisition import" and "Create Release" and hoping a PO should have been created  but PO is NOT getting created.