Insert ข้อมูลเข้าฐานข้อมูลไม่ได้และไม่ขึ้นerror

คือลองเช็คโค้ดดูแล้วค่ะแต่ยังหาส่วนที่ผิดไม่เจอค่ะ :-; รบกวนช่วยดูให้หน่อยค่ะ

นี่โค้ดส่วนแรกค่ะ
<?ob_start();?>
<?php
session_start();
 if($_SESSION[username]=="") {
    echo "<script>alert('กรุณาเข้าสู่ระบบ')</script>";
    echo "<META HTTP-EQUIV=\"Refresh\" CONTENT=\"2;URL=login.php\">";
    exit();
 }
?>
<?php
      $con= mysqli_connect("localhost","root","12345678","projects") or die("Error: " . mysqli_error($con));
      mysqli_query($con, "SET NAMES 'utf8' ");
      error_reporting( error_reporting() & ~E_NOTICE );
      date_default_timezone_set('Asia/Bangkok');
?>
<html lang="en">
<head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
    <meta name="description" content="">
    <meta name="author" content="">
  
  <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>ระบบลาของบุคลากร วิทยาลัยอาชีวศึกษาสุราษฎร์ธานี</title>
  
  
  
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/js/bootstrap.min.js"></script>
  
    <!-- Custom fonts for this template-->
    <link href="vendor/fontawesome-free/css/all.min.css" rel="stylesheet" type="text/css">
    <link
        href="https://fonts.googleapis.com/css?family=Nunito:200,200i,300,300i,400,400i,600,600i,700,700i,800,800i,900,900i"
        rel="stylesheet">
    <!-- Custom styles for this template-->
    <link href="css/sb-admin-2.min.css" rel="stylesheet">
</head>
<body id="page-top">
  
    <!-- Page Wrapper -->
    <div id="wrapper">
        <!-- Sidebar -->
        <ul class="navbar-nav bg-gradient-primary sidebar sidebar-dark accordion" id="accordionSidebar">
<br>
            <!-- Sidebar - Brand -->
            <a class="sidebar-brand d-flex align-items-center justify-content-center" href="index.php">
                    <IMG SRC= "img/svc.png" width="95">    
            </a>
<br>
            <!-- Divider -->
            <hr class="sidebar-divider my-0">
            <!-- Nav Item - Dashboard -->
            <li class="nav-item active">
                <a class="nav-link" href="index.php">
                    <i class="fas fa-home"></i>
                    <span>หน้าแรก</span></a>
      </li>
            <!-- Divider -->
            <hr class="sidebar-divider">
            <!-- Heading -->
            <div class="sidebar-heading">
                ผู้ใช้งาน
            </div>
      <li class="nav-item">
                <a class="nav-link collapsed" href="#" data-toggle="collapse" data-target="#collapseUtilities"
                    aria-expanded="true" aria-controls="collapseUtilities">
                    <i class="fas fa-fw fa-wrench"></i>
                    <span>ข้อมูลบุคลากร</span>
                </a>
                <div id="collapseUtilities" class="collapse" aria-labelledby="headingUtilities"
                    data-parent="#accordionSidebar">
                    <div class="bg-white py-2 collapse-inner rounded">
                        <h6 class="collapse-header">ข้อมูลบุคลากร</h6>
                        <a class="collapse-item" href="profile.php">ข้อมูลบุคลากร</a>
                    </div>
                </div>
            </li>
      
            <div class="sidebar-heading">
                ผู้ดูแลระบบ
            </div>
            <!-- Nav Item - Pages Collapse Menu -->
            <li class="nav-item">
                <a class="nav-link collapsed" href="#" data-toggle="collapse" data-target="#collapseTwo"
                    aria-expanded="true" aria-controls="collapseTwo">
                    <i class="fas fa-fw fa-cog"></i>
                    <span>การเพิ่ม ลบ แก้ไขข้อมูล</span>
                </a>
                <div id="collapseTwo" class="collapse" aria-labelledby="headingTwo" data-parent="#accordionSidebar">
                    <div class="bg-white py-2 collapse-inner rounded">
                        <h6 class="collapse-header">การเพิ่ม ลบ แก้ไขข้อมูล</h6>
                        <a class="collapse-item" href="leavetype.php">ประเภทการลา</a>
            <a class="collapse-item" href="department.php">แผนก</a>
                        <a class="collapse-item" href="division.php">งาน</a>
            <a class="collapse-item" href="member.php">บุคลากร</a>
            <a class="collapse-item" href="position.php">ตำแหน่ง</a>
            <a class="collapse-item" href="levelstatus.php">การให้สิทธิ์ผู้ใช้</a>
            <a class="collapse-item" href="prename.php">คำนำหน้าชื่อ</a>
        </div>
                </div>
            </li>
            <!-- Nav Item - Utilities Collapse Menu -->
            

            <!-- Divider -->
            <hr class="sidebar-divider d-none d-md-block">
            <!-- Sidebar Toggler (Sidebar) -->
            <div class="text-center d-none d-md-inline">
                <button class="rounded-circle border-0" id="sidebarToggle"></button>
            </div>
            <!-- Sidebar Message -->
            
        </ul>
        <!-- End of Sidebar -->
        <!-- Content Wrapper -->
        <div id="content-wrapper" class="d-flex flex-column">
            <!-- Main Content -->
            <div id="content">
                <!-- Topbar -->
                <nav class="navbar navbar-expand navbar-light bg-white topbar mb-4 static-top shadow">
                    <!-- Sidebar Toggle (Topbar) -->
                    <button id="sidebarToggleTop" class="btn btn-link d-md-none rounded-circle mr-3">
                        <i class="fa fa-bars"></i>
                    </button>
                    <!-- Topbar Search -->
                    <div class="input-group">
                          
                        </div>
                    <!-- Topbar Navbar -->
                    <ul class="navbar-nav ml-auto">
                        <!-- Nav Item - Search Dropdown (Visible Only XS) -->
                        <li class="nav-item dropdown no-arrow d-sm-none">
                            <a class="nav-link dropdown-toggle" href="#" id="searchDropdown" role="button"
                                data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                                <i class="fas fa-search fa-fw"></i>
                            </a>
                            <!-- Dropdown - Messages -->
                            <div class="dropdown-menu dropdown-menu-right p-3 shadow animated--grow-in"
                                aria-labelledby="searchDropdown">
                                <form class="form-inline mr-auto w-100 navbar-search">
                                    <div class="input-group">
                                        <input type="text" class="form-control bg-light border-0 small"
                                            placeholder="Search for..." aria-label="Search"
                                            aria-describedby="basic-addon2">
                                        <div class="input-group-append">
                                            <button class="btn btn-primary" type="button">
                                                <i class="fas fa-search fa-sm"></i>
                                            </button>
                                        </div>
                                    </div>
                                </form>
                            </div>
                        </li>
                        
                        <div class="topbar-divider d-none d-sm-block"></div>
                        <!-- Nav Item - User Information -->
                        <li class="nav-item dropdown no-arrow">
                            <a class="nav-link dropdown-toggle" href="#" id="userDropdown" role="button"
                                data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                <span class="mr-2 d-none d-lg-inline text-gray-600 small">
                  <?php echo $_SESSION[username];?>
                  
                </span>
                                <img class="img-profile rounded-circle"
                                    src="img/undraw_profile.svg">
                            </a>
                            <!-- Dropdown - User Information -->
                            <div class="dropdown-menu dropdown-menu-right shadow animated--grow-in"
                                aria-labelledby="userDropdown">
                                <a class="dropdown-item" href="profile.php">
                                    <i class="fas fa-user fa-sm fa-fw mr-2 text-gray-400"></i>
                  ข้อมูลบุคลากร
                                </a>
                                
                                <div class="dropdown-divider"></div>
                                <a class="dropdown-item" href="login.php">
                                    <i class="fas fa-sign-out-alt fa-sm fa-fw mr-2 text-gray-400"></i>
                  ออกจากระบบ
                                </a>
                            </div>
                        </li>
                    </ul>
                </nav>
                <!-- End of Topbar -->
                  <!-- Begin Page Content -->
                <div class="container-fluid">
                    <!-- Page Heading PDF -->
                    <div class="d-sm-flex align-items-center justify-content-between mb-4">
                        <h1 class="h3 mb-0 text-gray-800">เพิ่มบุคลากร</h1>
                        
                    </div>

  
                    <!-- Content Row -->
แสดงความคิดเห็น
Preview
โปรดศึกษาและยอมรับนโยบายข้อมูลส่วนบุคคลก่อนเริ่มใช้งาน อ่านเพิ่มเติมได้ที่นี่