[Investment]

Quizás es que no sean '' y sean null.

    Query1.SQL.Clear;
    Query1.SQL.Add('select *');
    Query1.SQL.Add('from Articulos.db');
    Query1.sql.Add('Where Inventariado is null);
    Query1.sql.Add('Order by Grupo,Marca,Talla,Modelo');
    Query1.Open;