Bagaimana Cara Membuat Form Edit dengan Modal (modal ane Error) Minta bantuan

index.php

<?php
  $no = 0;
  $modal=mysqli_query($koneksi,"SELECT * FROM kelas");
  while($kelas=mysqli_fetch_array($modal)){
  $no++;

?>

    <tr>
      <th > <input type="checkbox" id="checkbox3">
                    <label for="checkbox3"></label></th>
      <th scope="row"><?php echo $no;?></th>
      <td><?php echo $kelas[id_kelas];?></td>
      <td><?php echo $kelas[kelas];?></td>
      <td><?php echo $kelas[nama_kelas];?></td>
      <td><?php echo $kelas[quantitas];?></td>
      <td>
	 		<a class="blue-text"><i class="fa fa-user"></i></a>
          <a class="teal-text" id="edit" data-target="#Edit_Kelas" data-toggle="modal" data-id="<?php echo  $kelas['id_kelas']; ?>"><i class="fa fa-pencil"></i></a>
          <a class="red-text" data-target="#Hapus_Kelas" data-toggle="modal" onclick="confirm_modal('hapus_kelas.php?&id_kelas=<?php echo  $kelas['id_kelas']; ?>');"><i class="fa fa-times"></i></a></td>
    </tr>

<?php
}
?>
<div id="Edit_Kelas" class="modal fade" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
</div>

<script type="text/javascript">



   $("#edit").click(function(e) { //panggil class
      var m = $(this).attr("id");
		   $.ajax({
    			   url: "modal_kelas.php", //Get halaman
    			   type: "GET",
    			   data : {id_kelas: m,}, //variabel yang diambil
    			   success: function (ajaxData){
      			   $("#Edit_Kelas").html(ajaxData);
      			   $("#Edit_Kelas").modal('show',{backdrop: 'true'});
      		   }
    		   });
        });
</script>

file modal_kelas.php

<?php
    include "koneksi.php";
	$id_kelas=$_GET['id_kelas'];
	$modal=mysqli_query($koneksi,"SELECT * FROM kelas WHERE id_kelas='$id_kelas'");
	while($edit=mysqli_fetch_array($modal)){
?>

    <div class="modal-content">

    	<div class="modal-header">
            <button type="button" class="close" data-dismiss="modal" aria-hidden="true">×</button>
            <h4 class="modal-title" id="myModalLabel">Edit Kelas</h4>
        </div>

        <div class="modal-body">
        	<form action="proses_edit.php" name="modal_popup" enctype="multipart/form-data" method="POST">

                <div class="form-group" style="padding-bottom: 20px;">
                	<label for="Modal Name">Kelas</label>
                    <input type="hidden" name="id_kelas"  class="form-control" value="<?php echo $edit['id_kelas']; ?>" />
     				<input type="text" name="kelas"  class="form-control" value="<?php echo $edit['kelas']; ?>"/>
                </div>

                <div class="form-group" style="padding-bottom: 20px;">
					<label for="Description">Nama Kelas</label>
     				<textarea name="description"  class="form-control"><?php echo $edit['nama_kelas']; ?></textarea>
                </div>

                <div class="form-group" style="padding-bottom: 20px;">
                	<label for="Date">Quantitas</label>
     				<input type="text" name="quantitas"  class="form-control" value="<?php echo $edit['quantitas']; ?>" disabled/>
                </div>

	            <div class="modal-footer">
	                <button class="btn btn-success" type="submit">
	                    Confirm
	                </button>

	                <button type="reset" class="btn btn-danger"  data-dismiss="modal" aria-hidden="true">
	               		Cancel
	                </button>
	            </div>

            	</form>

             <?php } ?>

            </div>


        </div>

file proses_edit.php

<?php
	include "koneksi.php";
	$id_kelas=$_POST['id_kelas'];
	$kelas = $_POST['kelas'];
	$nama_kelas = $_POST['nama_kelas'];
	$quantitas = $_POST['quantitas'];
	$modal=mysqli_query($koneksi,"UPDATE kelas SET kelas = '$kelas', nama_kelas='$nama_kelas', quantitas='$quantitas' WHERE id_kelas = '$id_kelas'");
	header('location:index.php?mod=kelas');
?>

pass di firebug ada errornya, mohon bantuannya, padahal sudah saya samakan kyak di contoh aguzribudy. tp masih g bisa ngirim query edit maupun load data yang di edit ke modal. mohon bantuannya