PDO insert not working on post when I click insert

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Javascript

PDO

I have the following code which for some reason does not seem to insert the data into the database. Please help:

Index.php <SCRIPT>
$("#insert").click(function(e) {
    $.ajax({
        url: ["./required/orderaction.php"],
        type: "POST",
        data: $("#add-form-data").serialize() + "&action=insert",
        success: function(response) {
            console.log(amodate);
            Swal.fire({
                title: 'Order added successfully!',
                showConfirmButton: false,
                type: 'success',
                icon: 'success',
                timer: 500,
                timerProgressBar: true,
            })

            $("#addOrderModal").modal("hide");
            
            ShowAllOrders();
        }
    });
});

orderaction.php

if (isset($_POST['action']) && $_POST['action'] == "insert") {
    $odate = $_POST['amodate'];
    $oclient = $_POST['amoclient'];
    $ocode = $_POST['amoprojectcodes'];
    $oname = $_POST['amoprojectname'];
    $otype = $_POST['amotype'];
    $oamount = $_POST['amoamount'];

    $db->insert($odate, $oclient, $ocode, $oname, $otype, $oamount);
}

db.php

// private $dsn = "sqlsrv:Server=localhost;Database=test";    // Conect with SQLServer
private $dsn = "mysql:host=localhost;dbname=limardfeng";   // Conect with MySQL
private $username = "root";
private $pass = "";
public $conn;

public function __construct()
{
    try {
        $this->conn = new PDO($this->dsn, $this->username, $this->pass);
        // echo "Succesfully Conected!";
    } catch (PDOException $e) {
        echo $e->getMessage();
    }
}

public function insert($odate, $oclient, $ocode, $oname, $otype, $oamount)
{
    $sql = "INSERT INTO tbl_order (odate, oclient, ocode, oname, otype, oamount) VALUES (:amodate,:amoclient,:amoprojectcodes,:amoprojectname,:amotype,:amoamount)";
    $stmt = $this->conn->prepare($sql);
    $stmt->execute(['amodate' => $odate, 'amoclient' => $oclient, 'amoprojectcodes' => $ocode, 'amoprojectname' => $oname, 'amotype' => $otype, 'amoamount' => $oamount]);
    return true;       
}

What I have tried:

I have similar code to the above which works on others however this does not work, the script code shows that it works in the inspection when I add "console.log("Works");" to it but other than that I am stumpt. Please help.