undefined index error

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<link rel="stylesheet" type="text/css" href="css/admin.css">
<link rel="stylesheet" type="text/css" href="css/bootstrap.css">
	<script type="text/javascript" src="js/jquery.js"></script>
	<script type="text/javascript" src="js/bootstrap.js"></script>
	<script src="js/jquery-3.1.1.min.js"></script>
<title>Halaman Admin - Tambah Admin</title>
</head>

<body>
<div id="header">
	<img src="images/header.png"/>
</div>
<?php

	include 'dashboard.php';

?>
<div id="isi-admin">
<h1>Tambah Data Administrator</h1><hr>
	<form method="POST" action="add-admin.php">
	<div class="form-group" align="center">
		<div style="width: 70%;">
				<li style="list-style-type: none; margin: 10px;">
				<h4 style="text-align: left; margin-top: 10px; margin-bottom: -10px;">Nama Lengkap</h4><br>
				<input class="form-control" type="text" id="nama" name="nama" required>
				</li><br/>
				<li style="list-style-type: none; margin: 10px;">
				<h4 style="text-align: left; margin-top: 10px; margin-bottom: -10px;">Email</h4><br>
				<input class="form-control" type="email" id="email" name="email" required>
				</li><br/>
				<li style="list-style-type: none; margin: 10px;">
				<h4 style="text-align: left; margin-top: 10px; margin-bottom: -10px;">Username</h4><br>
				<input class="form-control" type="text" id="username" name="username" required>
				</li><br/>
				<li style="list-style-type: none; margin: 10px;">
				<h4 style="text-align: left; margin-top: 10px; margin-bottom: -10px;">Password</h4><br>
				<input class="form-control" type="password" id="password" name="password" required>
				</li><br/>
				<li style="list-style-type: none; margin: 10px;">
				<h4 style="text-align: left; margin-top: 10px; margin-bottom: -10px;">Foto</h4><br>
				<input class="form-control" type="file" id="image" name="image"/>
				</li><br/>
		</div>
	</div>
			<center>
				<input class="btn btn-success" type="submit" value="SUBMIT" name="sub_btn"/>
				<input class="btn btn-danger" type="reset" value="RESET" name="res_btn"/>
			</center>
</form>


<?php

	if(isset($_POST['sub_btn'])){

		$target = "foto_admin/".basename($_FILES['image']['name']);

		include 'konek.php';

		$nama = $_POST['nama'];
		$email = $_POST['email'];
		$user = $_POST['username'];
		$pass = $_POST['password'];
		$gbr = $_FILES['image']['name'];

		$pass=md5($pass);

		$sql = "INSERT INTO user (nama, email, username , password, image) VALUES ('$nama','$email','$user','$pass','$gbr')";
		mysqli_query($connect,$sql);

		if (move_uploaded_file($_FILES['image']['tmp_name'], $target))
		{
			echo '<script language="javascript">';
			echo 'alert("Data Berita Berhasil Di Posting")';
			echo '</script>';
		}else{
			echo '<script language="javascript">';
			echo 'alert("Data Berita Gagal Di Posting")';
			echo '</script>';
		}

	}

?>
</div>
</body>
</html>