datetime - Mailing list pgsql-general

Hi,
i have a table Test with following fields
Id int
Expires int
The below query works perfectly fine on PostgreSQL version 7.0

select TO_CHAR(TIMESTAMP(datetime(Expires)), 'DD-MM-YYYY HH:MI AM') from
Test;

 But it doesn't work on PostgreSQL version 7.2 On PostgreSQL version 7.2
i get following error
ERROR:  parser: parse error at or near "datetime"
Please inform me what changes i have to make.
Regards,
pramod