Cant insert data into database

hy guys need help…
im new in website things so i hope u guys can help me why i cant insert data into database
this is my code for connection

	$host = "localhost";
	$user = "id10181935_xxx";
	$pass = "■■■";
	$db	  = "■■■";
	$link= mysqli_connect($host, $user, $pass, $db);

		echo "Failed to connect to MySQL";

and this is for the add 

// koneksi database
include 'koneksi.php';
// menangkap data yang di kirim dari form
$nopermohonan = $_POST['nopermohonan'];
$nosurat = $_POST['nosurat'];
$npwp = $_POST['npwp'];
$nama = $_POST['nama'];
$tanggalsurat = $_POST['tanggalsurat'];
$penanganan_kasus_satu = $_POST['penanganan_kasus_satu'];
$penanganan_kasus_dua = $_POST['penanganan_kasus_dua'];
$penanganan_kasus_tiga = $_POST['penanganan_kasus_tiga'];
$penanganan_kasus_empat = $_POST['penanganan_kasus_empat'];
// menginput data ke database
mysqli_query($link,"INSERT INTO tbl_pemindahan_bukuan VALUES('','$nopermohonan','$nosurat','$npwp','$nama','$tanggalsurat','$penanganan_kasus_satu','$penanganan_kasus_dua','$penanganan_kasus_tiga','$penanganan_kasus_empat')");
// mengalihkan halaman kembali ke index.php
echo '<script type="text/javascript">alert("Data Tersimpan");</script>';


i dont know where the error is tx btw…