::text problem

Hi ,

I am running postgres 7.3.4 on Linux 7.2. I wanna print 'Not Supplied' if 'c1' column of datatype - 'timestamp' is null. For that I am using case statement

SELECT
CASE WHEN c1 IS NULL THEN 'Record_Not_Found'ELSE c1 END as approval_date
FROM t1;
ERROR: Bad timestamp external representation 'Record_Not_Found'

SELECT
CASE WHEN c1 IS NULL THEN 'Record_Not_Found'::text ELSE c1 END as approval_date
FROM t1;
ERROR: CASE types 'timestamp without time zone' and 'text' not matched

Where I am doing wrong? Please shed some light.

Regards
Senthil Kumar S
DBA