Error saat get data di array php aplikasi absensi

Halo selamat siang, saya sedang coba buat aplikasi untuk absensi karyawan, nah saat saya sedang coba input data dari array yang saya buat, hasilnya ada error seperti ini. Mohon bantuannya teman teman untuk mengatasi error tersebut.

<a href='https://prnt.sc/q3n62m'>Error</a>

CODING UNTUK FORM ---------------------------------------------------------

<form action="aksi_absensi.php?act=create" method="post" class="m-form m-form--fit m-form--label-align-right">
<table class="m-datatable" id="html_table" width="100%">
<thead>
<tr>
	<th>No</th>
	<th>NIK</th>
	<th>Nama karyawan</th>
	<th>Jabatan</th>
	<th>Masuk</th>
	<th>Sakit</th>
	<th>Ijin</th>
	<th>Absen</th>
	<th>Lembur</th>
	<th>Potongan</th>
</tr>
</thead>
<tbody>
	<?php
	$no=1;
	$sqlCreate = mysqli_query($conn, "SELECT * FROM tb_karyawan
	INNER JOIN tb_jabatan ON tb_karyawan.id_jabatan = tb_jabatan.id_jabatan
	WHERE NOT EXISTS (SELECT * FROM tb_absensi WHERE bulan = '$bulantahun' AND
        tb_karyawan.nik=tb_absensi.nik)");

	$jmlKaryawan = mysqli_num_rows($sqlCreate);
	while ($rowC = mysqli_fetch_array($sqlCreate)) { ?>
	<input type="hidden" name="bulan[]" value="<?php echo $bulantahun; ?>">
	<input type="hidden" name="nik[]" value="<?php echo $rowC['nik']; ?>">
	<tr>
	<td><?php echo $no;?></td>
	<td><?php echo $rowC['nik']; ?></td>
	<td><?php echo $rowC['nama_karyawan']; ?></td>
	<td><?php echo $rowC['nama_jabatan']; ?></td>
	<td><input type="text" name="masuk" class="form-control col-6" value="0" required></td>
	<td><input type="text" name="sakit" class="form-control col-6" value="0" required></td>
	<td><input type="text" name="ijin" class="form-control col-6" value="0" required></td>
	<td><input type="text" name="absen" class="form-control col-6" value="0" required></td>
	<td><input type="text" name="lembur" class="form-control col-6" value="0" required></td>
	<td><input type="text" name="potongan" class="form-control col-10" value="0" required></td>
	</tr>

	<?php  $no++;
	} if ($jmlKaryawan > 0) {  ?>
</tbody>
	<button type="submit" class="btn btn-primary btn-sm"><i class="la la-save"></i> Simpan</button> | <button type="reset" class="btn btn-danger btn-sm"><i class="la la-times-circle"></i> Batal</button>
	<br><br>
	<?php
	}else{ ?>
	<div class="alert alert-danger" role="alert">
	<strong>MAAF!</strong> Data bulan <strong style="color: yellow;"><?php echo $bulan; ?></strong> ini sudah di proses, silahkan pilih bulan lain.</div>
	<?php
	}
	?>
</table>
</form>

CODING UNTUK ACTION PHP ---------------------------------------------------------

<?php
session_start();
include 'conf/conn.php';
if (!isset($_SESSION['login'])) {
	header("location:index.php");
}
if (isset($_GET['act'])) {
	// Insert Data
	if ($_GET['act']=='create') {
	# Prorses simpan data
	$bulan 		= $_POST['bulan'];   //Line 11
	$nik 		= $_POST['nik'];     //Line 12
	$sakit 		= $_POST['sakit'];
	$ijin 		= $_POST['ijin'];
	$absen 		= $_POST['absen'];
	$lembur 	= $_POST['lembur'];
	$potongan 	= $_POST['potongan'];

	// Hitung data yang masuk
	$count 	= count($nik);   //Line 20

	$sql 	= "INSERT INTO tb_absensi(bulan,nik,sakit,ijin,absen,lembur,potongan) VALUES";
	for ($i=0; $i > $count ; $i++) {

// sambung SQL nya dibawah ini
                $sql .= "('{$bulan[$i]}','{$nik[$i]}','{$sakit[$i]}','{$ijin[$i]}','{$absen[$i]}',
                '{$lembur[$i]}','{$potongan[$i]}')";

		$sql .= " , ";
		}
		$sql .= rtrim($sql," , ");

		// Untuk Simpan
		$simpan = mysqli_query($conn, $sql);
		if ($simpan) {
			echo ("<script LANGUAGE='JavaScript'>
				window.alert('SUKSES! Data Berhasil Disimpan.');
				window.location.href='data_absensi.php';
				</script>");
		}else{
			("<script LANGUAGE='JavaScript'>
			window.alert('ERROR, GAGAL SIMPAN DATA');
			window.location.href='data_absensi.php?view=create';
			</script>");
		}
	}
?>