Error Chart.js in Laravel?

I'm trying to use Chart.js in Laravel through their own lib, but it returns the following error: Call to undefined method Fx3costa \ LaravelChartJs \ Builder :: size ()

I do not know what can be, I did everything the way the documentation says without taking or for, follow my controller, I'm using version 5.3:

<?php

namespace App\Http\Controllers\Admin;

use Illuminate\Http\Request;
use App\Http\Controllers\Controller;

class DashboardController extends Controller
{
    public function index()
    {

        $graficos['vendas'] = app()->chartjs
            ->name('lineChartTest')
            ->type('line')
            ->size(['width' => 400, 'height' => 200])
            ->labels(['January', 'February', 'March', 'April', 'May', 'June', 'July'])
            ->datasets([
                [
                    "label" => "My First dataset",
                    'backgroundColor' => "rgba(38, 185, 154, 0.31)",
                    'borderColor' => "rgba(38, 185, 154, 0.7)",
                    "pointBorderColor" => "rgba(38, 185, 154, 0.7)",
                    "pointBackgroundColor" => "rgba(38, 185, 154, 0.7)",
                    "pointHoverBackgroundColor" => "#fff",
                    "pointHoverBorderColor" => "rgba(220,220,220,1)",
                    'data' => [65, 59, 80, 81, 56, 55, 40],
                ],
                [
                    "label" => "My Second dataset",
                    'backgroundColor' => "rgba(38, 185, 154, 0.31)",
                    'borderColor' => "rgba(38, 185, 154, 0.7)",
                    "pointBorderColor" => "rgba(38, 185, 154, 0.7)",
                    "pointBackgroundColor" => "rgba(38, 185, 154, 0.7)",
                    "pointHoverBackgroundColor" => "#fff",
                    "pointHoverBorderColor" => "rgba(220,220,220,1)",
                    'data' => [12, 33, 44, 44, 55, 23, 40],
                ]
            ])
            ->options([]);

        $graficos['financas'] = app()->chartjs
            ->name('pieChartTest')
            ->type('pie')
            ->size(['width' => 400, 'height' => 200])
            ->labels(['Label x', 'Label y'])
            ->datasets([
                [
                    'backgroundColor' => ['#FF6384', '#36A2EB'],
                    'hoverBackgroundColor' => ['#FF6384', '#36A2EB'],
                    'data' => [69, 59]
                ]
            ])
            ->options([]);

        $pagina['titulo_pagina'] = "Dashboard";
        return view('admin/dashboard/dashboard', compact('graficos', 'pagina'));
    }
}