Oracle Database Discussions

I am using a spool command to export a table to a flat file. But I am not seeing any data on output file but it creates a balnk file.

here is the code that I am using

SET termout OFF;
SET feedback OFF;
SET pagesize 0;
SET linesize 800;
SET heading OFF;
SET TRIMOUT ON;
SET trimspool ON;
SPOOL \\accdf\public\abc.txt append
SELECT id
|| '|'
|| Message
|| '|'
|| body
|| '|'
|| ROOM_No
|| '|'
|| ROOM_Cat
|| '|'
|| USER_No
|| '|'
|| Cdate

FROM D_Mail_HISTORY;

SPOOL OFF;