In an add page I want to filter a select option field by a numeric editable field named "idgroup". So I put in the select data source of the select option field the sql in this way: "SELECT DISTINCT iduser AS value, username AS label FROM users WHERE idgroup= ?" and in the query params "$lookup_idgroup" but it doensn't work (no records returned), like it was unable to retrieve the value from the idgroup field or to update the select datasource after the page is loaded.