How to import Standard Purchase Order in Approved Status

Hi,

I am trying to import purchase order using Import Standard Purchase Orders (PDOI), my requirement is to import purchase order in approved status, but they are importing in incomplete status, I am using po_headers_interface, po_lines_interface and I am populating approval status column with approved in caps, and while running import request I am selecting the approved from list of values but not able to import purchase order in approved status.

Any help on this???

Regards