[MonetDB-users] trigger ambiguous issue

I have following trigger statement: CREATE TRIGGER delete_pos_cp AFTER DELETE ON cp referencing old row as o FOR EACH ROW WHEN o.new_id_ IS NOT NULL UPDATE cp SET old_id_ = o.old_id_ WHERE rec_id_ = o.rec_id_;

Following error is issued: SELECT: identifier 'rec_id_' ambiguous

The last "o.rec_id_" gives rise to this ambigious. Any suggestion on this.