Does not contain a definition for InsertOnSubmit

After receiving the data I try to insert them, however InsertOnSubmit sends me a message that says "DBSET does not contain a definition.

BastionContext ctx = new BastionContext();

        vehiculos_bastion us = new vehiculos_bastion
        {
            codigo = codigo,
            marca = marca,
            matricula = matricula,
            anio = anio,
            color = color,
            kilometraje = kilometraje,
            combustible = combustible,
            numSerie = numSerie,
            numMotor = numMotor,
            tipo = tipo,
            largo = largo,
            ancho = ancho,
            altura = altura,
            tonelada = tonelada,
            comentarios = comentarios,
            fechaAlta = fechaAlta,
            estatus = estatus
        };

        ctx.vehiculos_bastion.InsertOnSubmit(us);