Question: data different between PO tables and forms

 Hi everyone,

This question might have a very simple question but I just couldn't figure it out.

For some of our POs, amount_billed are different between tables and forms, and right now I have about 10 such POs.  For example, there is a PO with 1000 in po_line_locations_all and po_distributions_all tables.  When I view it from Apps, however, the form shows a little less amount, like 950.  I thought it is because of column 'order_type_lookup_code' in po_lines_all table, but when I checked code behind for the views, it seems not.

Any suggestion or comment will be highly appreciated.