My Trigger is not working :(

I think i missed some basics ...

ERROR: column "ad_table_id" does not exist

  Where: PL/pgSQL function "oms_changelog" line 21 at assignment

CREATE TABLE ad_changelog

(

  ad_changelog_id numeric(10,0) NOT NULL,

  ad_session_id numeric(10,0) NOT NULL,

  ad_table_id numeric(10,0) NOT NULL,

  ad_column_id numeric(10,0) NOT NULL,

  ad_client_id numeric(10,0) NOT NULL,

  ad_org_id numeric(10,0) NOT NULL,

  isactive character(1) NOT NULL DEFAULT 'Y'::bpchar,

  created timestamp without time zone NOT NULL DEFAULT now(),

  createdby numeric(10,0) NOT NULL,

  updated timestamp without time zone NOT NULL DEFAULT now(),

  updatedby numeric(10,0) NOT NULL,

  record_id numeric(10,0) NOT NULL,

  oldvalue character varying(2000),

  newvalue character varying(2000),

  undo character(1),

  redo character(1),

  iscustomization character(1) NOT NULL DEFAULT 'N'::bpchar,

  trxname character varying(60),

  description character varying(255),

  eventchangelog character(1),

  CONSTRAINT ad_changelog_pkey PRIMARY KEY (ad_changelog_id, ad_session_id, ad_table_id, ad_column_id),

  CONSTRAINT adcolumn_adchangelog FOREIGN KEY (ad_column_id)

      REFERENCES ad_column (ad_column_id) MATCH SIMPLE

      ON UPDATE NO ACTION ON DELETE CASCADE DEFERRABLE INITIALLY DEFERRED,

  CONSTRAINT adsession_adchangelog FOREIGN KEY (ad_session_id)

      REFERENCES ad_session (ad_session_id) MATCH SIMPLE

      ON UPDATE NO ACTION ON DELETE NO ACTION DEFERRABLE INITIALLY DEFERRED,

  CONSTRAINT adtable_adchangelog FOREIGN KEY (ad_table_id)

      REFERENCES ad_table (ad_table_id) MATCH SIMPLE

      ON UPDATE NO ACTION ON DELETE CASCADE DEFERRABLE INITIALLY DEFERRED,

  CONSTRAINT ad_changelog_isactive_check CHECK (isactive = ANY (ARRAY['Y'::bpchar, 'N'::bpchar])),

  CONSTRAINT ad_changelog_iscustomization_check CHECK (iscustomization = ANY (ARRAY['Y'::bpchar, 'N'::bpchar]))

)

WITH (

  OIDS=FALSE

);

ALTER TABLE ad_changelog OWNER TO adempiere;

-- Index: ad_changelog_speed

-- DROP INDEX ad_changelog_speed;

CREATE INDEX ad_changelog_speed

  ON ad_changelog

  USING btree

  (ad_table_id, record_id);

-- Trigger: oms_changelog on ad_changelog

-- DROP TRIGGER oms_changelog ON ad_changelog;

CREATE TRIGGER oms_changelog

  BEFORE INSERT

  ON ad_changelog

  FOR EACH ROW

  EXECUTE PROCEDURE oms_changelog();