pl/pgsql NEW variable substitution

[jef peeraer <jef(dot)peeraer(at)telenet(dot)be>]

i want to check in a trigger if certain columns are not left empty. The 
columns i have to check are stored in another table. How do i do the 
following

BEGIN
	SELECT INTO col_record * FROM modules WHERE type_module_id = 
NEW.type_module_id AND is_afsluit_kolom;
	IF NOT FOUND THEN
		RAISE EXCEPTION 'geen afsluitkolom gedefinieerd voor type_module % ', 
NEW.type_module_id;
	ELSE
		col_naam := col_record.kolom_naam;
		RAISE NOTICE 'kolom to check is % ', col_naam;
		--- check if afsluitrecord is empty
		IF NEW.col_naam != '' THEN
			RETURN NEW;	
		ELSE
			RAISE EXCEPTION 'dit record is afgesloten voor wijzigingen !';
		END IF;
 	END IF;
END;


I want col_naam to be evaluated before used with NEW . Now i get a 
warning that the table the trigger is written for doesn't has a column 
'col_naam'.


jef peeraer