gambar yang di upload tidak bisa tampil di web.

assalamualaikum kak, mau tanya kenapa php upload gambar tidak bisa tampil di web, sedangkan di folder tempat penyimpanannya bisa (tampil)kak. gambar yang di upload tidak bisa tampil di web kak. ini kode ny kak

<?php
	include "koneksi.php";
    $sql = "select * FROM simpan";
    $tampil = mysql_query($sql);
    while ($data = mysql_query($tampil));{
    // Tampilkan gambar
    echo "<img src='gambar/" .$data['gambar']."' width='100px' height='100px'/>";
    echo "</br>";
    echo $data['keterangan'];
    }
 ?>

 <form method="post" enctype="multipart/form-data">
 <td colspan="4">uploadgambar (ukuran maks = 1mb): <input type="file" name="gambar" required /> | keterangan :
 <input type="text" name="keterangan" /> |
 <input type="submit" value="upload" name="save"></td>
 </form>

 <?php
 if (isset($_POST['save'])){
 	$filename = $_FILES['gambar'] ['name'];
    // simpan ke database
    $sql = "insert into simpan (gambar, keterangan) values ('$filename', '".$_POST['keterangan']."')";
    mysql_query($sql);
    // simpan di folder gambar
    move_uploaded_file($_FILES['gambar']['tmp_name'], "gambar/" .$_FILES['gambar']['name']);
    	echo"<script> alert ('gambar berhasil diupload !') history.go(-1);</script>";
        }
?>

mohon bantuan nya kak =)