404 not found attachment laravel

Ada yang punya solusi mengenai mengirim file menggunakan attachment di laravel. Saya sudah mencari permasalahannya tetapi tidak ketemu. Ada yang tau letak permasalahan dari kode saya.

SendEmail.php

<?php

namespace App\Mail;

use Illuminate\Bus\Queueable;
use Illuminate\Mail\Mailable;
use Illuminate\Queue\SerializesModels;
use Illuminate\Contracts\Queue\ShouldQueue;

class SendEmail extends Mailable
{
    use Queueable, SerializesModels;

    /**
     * Create a new message instance.
     *
     * @return void
     */

    public $ni;
    public $nam;
    public $alamat_seko;
    public $jud;
    public $pes;
    public $storagePath;

    public function __construct($nis,$nama,$alamat_sekolah,$judul,$pesan,$storagePath)
    {

        set_time_limit(8000000);

        $this->ni = $nis;
        $this->nam = $nama;
        $this->alamat_seko = $alamat_sekolah;
        $this->jud = $judul;
        $this->pes = $pesan;
        $this->attachmentFile = public_path() . '/' . $storagePath;
    }

    /**
     * Build the message.
     *
     * @return $this
     */
    public function build()
    {
        $e_nis = $this->ni;
        $e_nama = $this->nam;
        $e_alamat_sekolah = $this->alamat_seko;
        $e_judul = $this->jud;
        $e_pesan = $this->pes;
        return $this
        ->view('permohonan.template_mail', compact("e_pesan"))
        ->subject($e_judul)
        ->attach($this->attachmentFile);
    }
}

MailController.php

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;
use Illuminate\Support\Facades\Storage;
use Mail;
use Session;
use App\Student;
use App\Mail\SendEmail;

class MailController extends Controller
{
    //
    public function home()
    {
        return view('permohonan.index');
    }

    public function sendemail(Request $get)
    {
        $this->validate($get,[
            "email"=>"required",
            "nis"=>"required",
            "nama"=>"required",
            "alamat_sekolah"=>"required",
            "judul"=>"required",
            "pesan"=>"required",
        ]);

        $email = $get->email;
        $nis = $get->nis;
        $nama = $get->nama;
        $alamat_sekolah = $get->alamat_sekolah;
        $judul = $get->judul;
        $pesan = $get->pesan;

        $attachment = Student::findOrFail($get->id);
        $storagePath = Storage::url($attachment->attachmentPath);

        Session::flash("success");
        Mail::to($email)->send( new SendEmail($nis,$nama,$alamat_sekolah,$judul,$pesan,$storagePath));
        return back();

        dd($storagePath);
    }
}

index.blade.php

<form action="{{url('send/email')}}" method="POST" novalidate="novalidate">
                            {{ csrf_field() }}
                            @if (Session::has("success"))
                                @include('message.message')
                            @endif
                            <div class="form-group">
                                <label for="cc-payment" class="control-label mb-1">Email</label>
                                <input id="email" name="email" type="text" class="form-control">
                            </div>
                            <div class="form-group">
                                <label for="cc-payment" class="control-label mb-1">NIS</label>
                                <input id="nis" name="nis" type="text" class="form-control">
                            </div>
                            <div class="form-group has-success">
                                <label for="cc-name" class="control-label mb-1">Nama Siswa</label>
                                <input id="nama" name="nama" type="text" class="form-control cc-name valid">
                                <span class="help-block field-validation-valid" data-valmsg-for="cc-name" data-valmsg-replace="true"></span>
                            </div>
                            <div class="form-group">
                                <label for="cc-number" class="control-label mb-1">Alamat Sekolah</label>
                                <input id="alamat_sekolah" name="alamat_sekolah" type="text" class="form-control cc-number identified visa" value="">
                                <span class="help-block" data-valmsg-for="cc-number" data-valmsg-replace="true"></span>
                            </div>
                            <div class="form-group">
                                <label for="cc-number" class="control-label mb-1">Judul</label>
                                <input id="judul" name="judul" type="text" class="form-control cc-number identified visa" value="">
                                <span class="help-block" data-valmsg-for="cc-number" data-valmsg-replace="true"></span>
                            </div>
                            <div class="form-group">
                                <label for="cc-number" class="control-label mb-1">Pesan</label>
                                ​<textarea rows="10" cols="70" id="pesan" name="pesan" type="textarea" class="form-control cc-number identified visa" value=""></textarea>
                                {{-- <input id="cc-number" name="pesan" type="textarea" class="form-control cc-number identified visa" value="" data-val="true" data-val-required="Please enter the card number" data-val-cc-number="Please enter a valid card number"> --}}
                                <span class="help-block" data-valmsg-for="cc-number" data-valmsg-replace="true"></span>
                            </div>
                            <div class="form-group">
                                <input id="file" name="attachment" type="file" class="form-control cc-number identified visa" value="">
                            </div>

                            <div>
                                <button id="payment-button" type="submit" class="btn btn-lg btn-info btn-block">

                                <span id="payment-button-amount">Kirim</span>
                                <span id="payment-button-sending" style="display:none;">Sending…</span>
                                </button>
                            </div>
                        </form>