bootstrap table and form not visible in php - php

Question

I am trying to get some data from a database and show them in a bootstrap table in php. but the php file only shows navigation bar. it does not show the table or the form. I have checked the connection which is fine. even if connection was wrong it should at least show the table headers and form labels. which it does not.
<?php
include 'adminlogincheck.php';
include 'dbcarsconfig.php';
include 'adminheader.php';
?>
<div class="container-fluid">
<div class="row justify-content-center">
<div class="col-md-8">
<!-- session response-->
<?php if(isset($_SESSION['response'])){ ?>
<div class="alert alert-<?= $_SESSION['res_type']; ?> alert-dismissible">
<button type="button" class="close" data-dismiss="alert">×</button>
<?= $_SESSION['response']; ?>
</div>
<?php } unset($_SESSION['response']);?>
<?php
$query="SELECT * FROM cars";
$stmt=$conn->prepare($query);
$stmt->execute();
$result=$stmt->get_result();
?>
<table class="table table-dark table-striped table-hover">
<thead>
<tr>
<th>Thumbnail</th>
<th>ID</th>
<th>Reg no</th>
<th>Make</th>
<th>Model</th>
<th>Price</th>
<th>Actions</th>
</tr>
</thead>
<tbody>
<?php while($row=$result->fetch_Assoc()){?>
<tr>
<td><img src="<?= $row['image1']?>" width="100" height="50"></td>
<td><?= $row['id']?></td>
<td><?= $row['carreg']?></td>
<td><?= $row['make']?></td>
<td><?= $row['model']?></td>
<td><?= $row['price']?></td>
<td> Edit/View</td>
<td> Delete</td>
</tr>
<?php } ?>
</tbody>
</table>
</div>
<div class="col-md-4">
<form action="actioncars.php" method="post" enctype="multipart/form-data">
<input type="hidden" name="id" value="<?= $id; ?>">
<div class="form-group">
<input type="text" name="carreg" class="form-control" placeholder="Enter car reg no" value="<?= $carreg; ?>" required>
</div>
<div class="form-group">
<input type="text" name="make" class="form-control" placeholder="Make of car" value="<?= $make; ?>" required>
</div>
<div class="form-group">
<input type="text" name="model" class="form-control" placeholder="Model" value="<?= $model; ?>" required>
</div>
<div class="form-group">
<input type="text" name="price" class="form-control" placeholder="Price" value="<?= $price; ?>" required>
</div>
<div class="form-group">
<input type="hidden" name="oldimage" value="<?= $image1; ?>">
<input type="file" name="image1" class="custom-file">
<img src="<?= $image1; ?>" width="120" class="img-thumbnail">
</div>
<div class="form-group">
<?php if ($update==true){ ?>
<input type="submit" name="update" class="btn btn-success btn-block" value="Update record">
<?php } else { ?>
<input type="submit" name="add" class="btn btn-primary btn-block" value="Add record">
<?php } ?>
</div>
</form>
</div>
</div>
</div>
<?php include 'footer.php'; ?>