Problems w/ PL/pgSQL not being loaded?

Hi all.

Once again, I'm trying to climb the learning curve...

I'm trying to write a trigger in PL/pgSQL to update some tables. When I try
to load the function, I get an error message:

The function is:

create function update_modified () returns opauqe as '
BEGIN
NEW.modified := ''now()'';
return 1;
END;
'
language 'plpgsql';

The error message indicates that I'm trying to us an unrecognized language.
The recognized languages are sql, C, internal and other created languages.
I've not loaded anything besides the default.

1. How do I load PL/pgSQL?

2. Does this function look right? It should change the a.modified field
upon update.

Thanx again,
Mike Diehl,
Network Monitoring Tool Devl.
284-3137
jdiehl(at)sandia(dot)gov