Calling triggers with arguments

Greetings,

I've come across something that either doesn't work spec'd or I'm
missing something (I suspect the latter). I'm trying this:

CREATE TRIGGER classified_index_trigger
BEFORE INSERT OR UPDATE ON ads
FOR EACH ROW
EXECUTE PROCEDURE htdig_index('classified_en');

and the error message I get is:

ERROR: function htdig_index() does not exist

However if I do \df htdig_index I get this:

List of functions
Result data type | Schema | Name | Argument data types
------------------+--------+-------------+---------------------
"trigger" | public | htdig_index | text

Is there something I'm missing in order to pass an argument in a
trigger? I've tried double quotes, and two singles as well as no
quotes, and all lead to the same thing.

Any info would be much appreciated.

Cheers,

Chris

--
Christopher Murtagh
Enterprise Systems Administrator
ISR / Web Communications Group
McGill University
Montreal, Quebec
Canada

Tel.: (514) 398-3122
Fax: (514) 398-2017