php 表单不发送日期到数据库 SQL

我用HTML和PHP设置了一个表单。我正在将从表单提交的所有信息发送到SQL数据库。当我提交表格时，我收到以下错误代码：

ERROR: Could not execute INSERT INTO `timesheets` (`Name`, `weekending`, `monin`, `monout`, `tuein`, `tueout`, `wedin`, `wedout`, `thursin`, `thursout`, `friin`, `friout`, `satin`, `satout`, `sunin`, `sunout`) VALUES ('Nathan Langer','07:30','16:00','18:00','19:00','06:30','15:00','03:00','16:00','05:00','16:00','00:00','00:00','00:00','00:00'). Column count doesn't match value count at row 1

正如你所看到的，日期没有被推到（应该在Nathan Langer和07：30之间。

我的提交代码如下：

<?php
/* Attempt MySQL server connection. Assuming you are running MySQL
server with default setting (user 'root' with no password) */
$link = mysqli_connect("localhost", "username", "pass", "dbname");
// Check connection
if($link === false){
die("ERROR: Could not connect. " . mysqli_connect_error());
}
// Escape user inputs for security
$Name = mysqli_real_escape_string($link, $_POST['Name']);
$insertdate = date('Y-m-d', strtotime($_POST['weekending']));
$monin = mysqli_real_escape_string($link, $_POST['monin']);
$monout = mysqli_real_escape_string($link, $_POST['monout']);
$tuein = mysqli_real_escape_string($link, $_POST['tuein']);
$tueout = mysqli_real_escape_string($link, $_POST['tueout']);
$wedin = mysqli_real_escape_string($link, $_POST['wedin']);
$wedout = mysqli_real_escape_string($link, $_POST['wedout']);
$thursin = mysqli_real_escape_string($link, $_POST['thursin']);
$thursout = mysqli_real_escape_string($link, $_POST['thursout']);
$friin = mysqli_real_escape_string($link, $_POST['friin']);
$friout = mysqli_real_escape_string($link, $_POST['friout']);
$satin = mysqli_real_escape_string($link, $_POST['satin']);
$satout = mysqli_real_escape_string($link, $_POST['satout']);
$sunin = mysqli_real_escape_string($link, $_POST['sunin']); 
$sunout = mysqli_real_escape_string($link, $_POST['sunout']);

// attempt insert query execution
$sql = "INSERT INTO `timesheets` (`Name`, `weekending`, `monin`, `monout`,      `tuein`, `tueout`, `wedin`, `wedout`, `thursin`, `thursout`, `friin`, `friout`, `satin`, `satout`, `sunin`, `sunout`) VALUES ('$Name','$monin','$monout','$tuein','$tueout','$wedin','$wedout','$thursin','$thursout','$friin','$friout','$satin','$satout','$sunin','$sunout')";
if(mysqli_query($link, $sql)){
header('location:timesheets.php');
} else{
echo "ERROR: Could not execute $sql. " . mysqli_error($link);
}
// close connection
mysqli_close($link);
?>

这是因为我在提交表单中的日期上做错了吗？ 表单中的日期字段如下：

<div class="col-md-6 col-sm-6" >
<div class="input-group">
<span class="input-group-addon">
<i class="fa fa-calendar"></i>
</span>
<input type="date" id="weekending" class="form-control " name="weekending" placeholder="Week Ending">
</div>                                              
</div>  

请有人帮我找到问题所在以及为什么它不会发布到数据库？