Trigger/Function problem

I'm having problems with a trigger/function and I think it's actually a
system problem but I have no clue how to fix it.  The trigger is supposed to
automatically timestamp the record when it is altered.

I've never used anything more than a sql function before so the plpgsql is
new to me.

Here's the info:

My table:
CREATE TABLE "help" (
   "help_id" int4 DEFAULT nextval('help_id_seq'::text) NOT NULL,
   "keyword" varchar(20) NOT NULL,
   "help_text" text NOT NULL,
   "auto_date" date NOT NULL,
   "title" varchar(50) DEFAULT 'Help Topic',
   "admin" bool DEFAULT 't',
   "site_id" varchar(5) DEFAULT '0',
   CONSTRAINT "help_pkey" PRIMARY KEY ("help_id")
);

My function:
CREATE FUNCTION "f_auto_date"() RETURNS OPAQUE AS '
BEGIN
  NEW.auto_date := ''now'';
  RETURN NEW;
END;
' LANGUAGE 'plpgsql';

My trigger:
CREATE TRIGGER "t_auto_date" BEFORE INSERT OR UPDATE ON "help" FOR EACH ROW
EXECUTE PROCEDURE "f_auto_date"();

I'm totally fine up to this point... then I try this:

UPDATE help SET site_id = 'APW' WHERE help_id = 2;

I get the following error:

NOTICE:  plpgsql: ERROR during compile of f_auto_date near line 1
"RROR:  parse error at or near "

I've tried the sample on the following web page as well:
http://www.postgresql.org/users-lounge/docs/7.0/user/c40874340.htm

And I get the exact same error (except of course the function name is
different). So I'm assuming that it's a problem in my system
configuration... I may be wrong.

I don't know how to fix this or even where to begin.  I do have plpgsql
installed as a language. I'm running PG 7.0.2 on standard RedHat 7 ... not
sure of the Kernel.

Thanks for your help,
-Dan