Variable tidak terbaca

nih gan masalah ane variable udah ane panggil via $_POST cuman ada 2 yg 1 di function.php yang ane include ke halaman tersebut dan satu lagi variable di dalam transaksi.php data yang di function bisa masuk cuman data yang dari file sewa.php ke file transaksi.php gak mau gmn klo ada via teamviewer biar jelas :3 bingung jelasinya <a href='https://www.facebook.com/Galang.blogger.mania'>https://www.facebook.com/Galang.blogger.mania</a>FB Contact

This is a problem this is a script

ini Script Fromnya

<?php include('header.php');?>
<?php include('../engine/config.php');?>
<div class="col-md-9">
	<div class="container">
		<div class='row'>
			<div class='col-md-12'>
				<div class='title'>Isi Form Sewa Berikut ini :</div>
						<form action='index.php' method='post'>
			<?php
			function password() {
				$gpass = NULL;
 $n = 6;
 $chr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvqxyz0123456789";
 for ($i = 0; $i < $n; $i++) {
 	$rIdx = rand(1, strlen($chr));
 	$gpass .=substr($chr, $rIdx, 1);
 }
 return $gpass;
} ?>
<div class='form-group'>
	<label>Kode Sewa</label>
	<input class="form-control" type="text" name="kode" value="<?php $abc =password(); echo $abc;?>">
</div>
<div class='form-group'>
	<label>Tempat Tujuan</label>
	<input type='text' class='form-control' name='tempat' placeholder='Surabaya' required/>
</div>
<div class='form-group'>
	<label>Tanggal Berangkat</label>
	<input type='date' class='form-control' name='berangkat' required/>
</div>
<div class='form-group'>
	<label>Tanggal Kembali</label>
	<input type='date' class='form-control' name='kembali' required/>
</div>
<div class='form-group'>
	<label>Pilih Supir</label>
	<select class="form-control" name="supir">
		<?php
		$query=mysql_query("SELECT * FROM supir");
		$no=1;
		while($lihat=mysql_fetch_array($query)){
			?>
			<option value="<?php echo $lihat['nama'];?>"><?php echo $lihat['nama'];?></option>

			<?php } ?>
		</select>
	</div>
	<div class="form-group mobil">
		<?php
		$query= mysql_query("SELECT * FROM mobil");
		while ($lihat=mysql_fetch_array($query)) { ?>

		<label><input type="radio" name="mobil" class="mob" value="<?php echo $lihat['gambar'];?>"><img src="../assets/images/<?php echo $lihat['gambar'];?>" width="200px" height="200px"></label>

		<?php } ?>
	</div>
	<?php
	$user = $_SESSION['user'];
$query=mysql_query("SELECT * FROM user WHERE username='$user'");
while ($lihat=mysql_fetch_array($query)) {?>
	<input type='hidden' value='<?php echo $lihat['username'];?>' name='username'>
	<input type='hidden' value='<?php echo $lihat['nama'];?>' name='nama'>
	<input type='hidden' value='<?php echo $lihat['email'];?>' name='email'>
		<?php }?>
	<input type='hidden' value='Rp.10.000,- /perday' name='denda'>
	<input type='hidden' value='add-sewa' name='act'/>
	<button class='btn btn-success float-md-right'>Selanjutnya</button>
</form>
				</div>
			</div>
		</div>

	</div>
	<?php include('footer.php');?>

ini functionya

}else if($act =='add-sewa') {
	$kode      = $_POST['kode'];
	$user      = $_POST['username'];
	$nama	   = $_POST['nama'];
	$email	   = $_POST['email'];
	$tempat	   = $_POST['tempat'];
	$berangkat = $_POST['berangkat'];
	$kembali   = $_POST['kembali'];
	$supir	   = $_POST['supir'];
	$mobil	   = $_POST['mobil'];
	$denda     = $_POST['denda'];

	$query =mysql_query("INSERT INTO sewa value('ID','$kode','$user','$nama','$email','$tempat','$berangkat','$kembali','$supir','$mobil','$denda')");
	if ($query) {
		echo '<script>alert("Silahkan Masuk Ketahap Pembembayaran ke Cs Kami !!"); document.location="transaksi.php";</script>';
	}else{
		echo '<script>alert("Gagal memasukan Data Coba ulangi sekali lagi !!"); document.location="sewa.php";</script>';
	}
}