Update Quote price using interface

Hi,

I am using PO_headers_interface, po_lines_interface and am trying to update an existing quote. When I insert data into headers and lines interface, it gives me an error saying "

Error: Column PRICE_OVERRIDE should not be NULL.

Error: Column PRICE_DISCOUNT should not be NULL." and the table it refers in po_line_locations_interface table. When I insert record into po_line_locations_interface, it does not give me an error, but it does not update the price either. In this case, On the price break form, the quantity is null after the update.

I am populating the following columns in the interface tables. Did anyone face similar issue ?