Filter the list in a combobox

Hi,
I want to filter the list in a combobox, from a datatable editor. When I use the where condition, I do not have any errors, but it does not return any records.

Editor::inst( $db, 'tb_diccionario' )
->field(
Field::inst( 'tb_diccionario.materia_id' )
->options( Options::inst()
->table( 'tb_materia' )
->value( 'id' )
->label( 'materia' )
->where( 'tb_materia.activo', 1 )
),
Field::inst( 'tb_materia.materia' ),

->leftJoin( 'tb_materia', 'tb_materia.id', '=', 'tb_diccionario.materia_id' )

*Activo es un campo de la tabla materia de tipo tinyint.