laravel中的ReflectionException。类不存在

Question

为什么laravel这次无法检测到我的课程。在我之前的尝试中，它有效，但这次没有。这是我的代码：

DataEntry.php

<?php namespace App\Server ;
abstract class DataEntry{
    /*This class facilitates the
     storing of data to the  server...
     */
    abstract protected function storeData($data);
    abstract protected function updateData($data ,$id);
}

MedicineDosageEntry.php

<?php 
namespace App\Server ; 
use Image; 
use App\Dosage ; 
use App\Photo ;
use App\Server\DataEntry ;  
use Request ; 
use Auth ;

class MedicineDosageEntry extends DataEntry{
    public function storeData ($data){
        $file = $data['photo'] ; 
        $fileName = uniqid().$file->getClientOriginalName() ; 
        if(!file_exists('medicine/images')){
            mkdir('medicine/images', 0777, true);
        }
        $file->move('medicine/images', $fileName);

        if(!file_exists('medicine/images/thumbs')){
            mkdir('medicine/images/thumbs', 0777, true);
        }

        $thumb = Image::make('medicine/images/' .$fileName)->resize(150,150)->save('medicine/images/thumbs/' . $fileName,50);
        $dosage = new Dosage;
        $dosage->dosage_name = $data['dosage_name'];
        $dosage->form = $data['form'];
        $dosage->medicine_id = $data['medicine_id'];
        $dosage->price = $data['price'];
        $dosage->save(); 

        $dosage->photo()->create([
            'dosage_id' => $data['id'];
            'file_name' => $fileName,
            'file_size' => $file->getClientSize(),
            'file_mime' => $file->getClientMimeType(),
            'file_path' => 'medicine/images/thumbs'. $fileName,
            'created_by'=> Auth::user()->id,
            ]);
    }


    public function updateData($data , $id) {

    }
}

MedicineController.php

<?php namespace App\Http\Controllers;
use Illuminate\Http\Request;
use App\DB\MedicineRepository;
use App\Http\Requests\MedicineRequest ;
use App\Dosage ;
use App\Medicine;
use Auth ;

use App\Server\MedicineDosageEntry ; 
use Flash ;

class MedicineController extends Controller {

public function store(MedicineRequest $request, MedicineDosageEntry $dosage ){
        $requestData = $request->all();
        $dosage->storeData($requestData);
    }

}

我必须注册这门课吗？为什么我会遇到这个。它在我之前的尝试中得到了解决，但在进行了一些重构和编码之后。它崩溃了..