Problem with session

I write the followings:

Route.php

 Route::get('/',function(){
    return view('welcome');   
  });

  Route::get('begin','sessionController@storeSessionData');

Controller

 class SessionController extends Controller
 {
  public function accessSessionData(Request $request){
  if($request->session()->has('my_name'))
     echo $request->session()->get('my_name');
  else
     echo 'No data in the session';
  }

  public function storeSessionData(Request $request){
      $request->session()->flash('flash_message','Virat Gandhi');
      $request->session()->flash('flash_message_level','error');
      return redirect('/');
  }

  public function deleteSessionData(Request $request){
     $request->session()->forget('my_name');
     echo "Data has been removed from session.";
  }
  }

welcome.blade.php

@extends('layouts.app')

    @section('content')
    <div class="container">
        @if (Session::has('flash_message'))
            <div class="Alert Alert--{{ ucwords(Session::get('flash_message_level'))}}">
             {{ Session::get('flash_message') }}
            </div>
         @endif

     <div class="row">
        <div class="col-md-10 col-md-offset-1">
           <div class="panel panel-default">
               <div class="panel-heading">Welcome</div>

            <div class="panel-body">
                Your Application's Landing Page.
              </div>
            </div>
         </div>
      </div>
   </div>
  @endsection

When I url to /begin the sessions are saved to variables but when I redirect to root the sessions dissapeared. Any suggestion?