Data chosen from select input isn’t known after uploading on the server but works on normal local host

So, before uploading on the server through cPanel, this code works fine. But on the server, I cannot.

On Server
On localhost

Both the codes are the same. It just doesn’t work on the website server. Please help me.

Here is the code snippet:

PHP CODE (below)

<?php
if(isset($_POST['form1'])) {
    $valid = 1;

    if(empty($_POST['tcat_id'])) {
        $valid = 0;
        $error_message .= "You must have to select a Main Menu<br>";
    }

    if(empty($_POST['mcat_name'])) {
        $valid = 0;
        $error_message .= "Sub Menu can not be empty<br>";
    }

    if($valid == 1) {

        // Saving data into the main table tbl_mid_category
        $statement = $pdo->prepare("INSERT INTO tbl_mid_category (mcat_name,tcat_id) VALUES (?,?)");
        $statement->execute(array($_POST['mcat_name'],$_POST['tcat_id']));
    
        $success_message = 'Sub Menu is added successfully.';
    }
}
?>

HTML FORM BELOW:

<form class="form-horizontal" action="" method="post">

                <div class="box box-info">
                    <div class="box-body">
                        <div class="form-group">
                            <label for="" class="col-sm-3 control-label">Main Menu Name <span>*</span></label>
                            <div class="col-sm-4">
                                <select name="tcat_id" class="form-control select2">
                                    <option value="">Select Main Menu</option>
                                    <?php
                                    $statement = $pdo->prepare("SELECT * FROM tbl_top_category ORDER BY tcat_name ASC");
                                    $statement->execute();
                                    $result = $statement->fetchAll(PDO::FETCH_ASSOC);   
                                    foreach ($result as $row) {
                                        ?>
                                        <option value="<?php echo $row['tcat_id']; ?>"><?php echo $row['tcat_name']; ?></option>
                                        <?php
                                    }
                                    ?>
                                </select>
                            </div>
                        </div>
                        <div class="form-group">
                            <label for="" class="col-sm-3 control-label">Sub Menu Name <span>*</span></label>
                            <div class="col-sm-4">
                                <input type="text" class="form-control" name="mcat_name">
                            </div>
                        </div>
                        
                        <div class="form-group">
                            <label for="" class="col-sm-3 control-label"></label>
                            <div class="col-sm-6">
                                <button type="submit" class="btn btn-success pull-left" name="form1">Submit</button>
                            </div>
                        </div>
                    </div>
                </div>

            </form>