Unable to fetch segment1 from po_headers_all in before insert trigger on po_lines_all

Hi All,

Need a small help on trigger on po_lines_all.

I need to insert some values to note_to_vendor column during the insertion of po_lines_all.

But I am not able to fetch segment1 from po_headers_all.

below is the script I am using.

Can anyone please check and let me know why I am not able to fetch segment1 from po_headers_all.

CREATE OR REPLACE TRIGGER apps.xx_po_lines_afi

  BEFORE INSERT

  ON po_lines_all

  FOR EACH ROW

DECLARE

  lc_flag             NUMBER;

  lc_po_number        VARCHAR2 (240);

  lc_note_to_vendor   VARCHAR2 (240);