ReflectionException in laravel. Class does not exist - laravel

Question

Why does laravel cannot detect my class this time. In my previous tries it worked but this time it does not. Here are my codes :
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);
}
}
Do i have to register this class. Why do I encounter this. It worked out in my previous tries but after doing some refactoring and coding. It crashed..