php artisan queue:work or listen not working Laravel 5.4

I have installed laravel 5.4 and want to confirm user registration, by email with queue, jobs table is created successfully, data are inserted as well in table user, but it outputs nothing when I run PHP artisan queue: work command. and I received nothing in my gmail box I've spent many hours to resolve it, but still not working. Any help would be really appreciated, thanks much.

Jobs/SendVerificationEmail Class:

    class SendVerificationEmail implements ShouldQueue
{
  protected $user;

    public function __construct($user)
    {
        $this->user = $user;
    }

    public function handle()
    {
        $data = ['email_token' => $this->user->email_token];

        Mail::send('email.email', $data, function($message) {
            $message->subject('This mail send by Queue Laravel 5.4');
            $message->to($this->user->email);
        });
    }
}

Contoller/RegistrationController class:

 class RegistrationController extends Controller
{
    public function create()
    {
        return view('register');
    }

    public function register(Request $request)
    {
        //create user
        $user = new User;
        $user->name = $request->name;
        $user->email = $request->email;
        $user->password = bcrypt($request->password);
        $user->email_token = base64_encode($request->email);

        $user->save();
        dispatch(new SendVerificationEmail($user));

        return view('verification');

        //add role by default the new registred saved as a User Role
        $user->roles()->attach(Role::where('name', 'User')->first());

        // redirect
        //return redirect('/posts');

        //login
        auth()->login($user);

    }
    public function verify($token)
    {
        $user = User::where('email_token',$token)->first();
        $user->verified = 1;
        if($user->save())
        {
            return view('emailconfirm',['user'=>$user]);
        }
    }
}

In the constructor of your SendVerificationEmail job set the connection and which queue you wan't to use, for example,

   public function __construct($user)
   {
        $this->queue = 'default'; //choose a queue name
        $this->connection = 'database';
        $this->user = $user;
   }

Then to start processing these jobs use the artisan command

 artisan queue:work database --queue=default

Also, in your SendVerificationEmail job add the line public $tries = 3; at the top of the file, now after this number of tries the job goes on the failed jobs queue and you can check the contents of the exception which put it there.