Class App\Http\Controllers\Api\DeliveryController does not exist

Other functions in the controller are working fine but the error shows up when I try to call this function.

I have checked through all the related posts but couldn't solve my problem.

Class App\Http\Controllers\StudentController does not exist in Laravel 5

https://laracasts.com/discuss/channels/laravel/class-apphttpcontrollersusercontroller-does-not-exist?page=1

The controller

<?php
namespace App\Http\Controllers;
use Illuminate\Support\Facades\DB;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Auth;
use App\Http\Controllers\Controller;
use Illuminate\Support\Facades\App;
use Illuminate\Support\Facades\Session;
use Illuminate\Support\Facades\URL;
use Illuminate\Support\Facades\Mail;
use App\Http\Controllers\CommonController;
use DateTime;
use Dompdf\Dompdf;
use Validator;
class DeliveryController extends Controller{

    public function __construct()
    {
        $this->middleware('auth');
    }
        //codes

       //The function in the controller
        public function fetchItemList($formId)
        {
        //codes
        return response()->json(['Item' => $item]);
        }

routes.php

Route::get('fetchItemList/{id}', 'Api\DeliveryController@fetchItemList');

via Chebli Mohamed