Php codeigniter自定义库未定义属性错误

我为我的支付网关创建了一个codeigniter自定义库（My_payment_gate_way_init）。。但当我使用自定义库函数时，控制器（计费）不会将参数传递到它显示的库中

A PHP Error was encountered

Severity: Notice

Message: Undefined property: Billing::$My_payment_gate_way_init

Filename: controllers/Billing.php

Line Number: 576

当我使用

控制器

    public function __construct()
        {
            parent::__construct();
            $this->load->library('My_payment_gate_way_init');
    }

function saveord(){
$ammount = $this->totlCost * 100;
$this->My_payment_gate_way_init->setTransactionAmountforPay($ammount);
}

库

class My_payment_gate_way_init
{

    private $clientConfig;
    private $initRequest;
    private $transactionAmount;
    private $redirect;
    private $initResponse;
    private $client;
    private $CI;
    function __construct()
    {
 $this->setTransactionAmountforPay();
}

  function setTransactionAmountforPay($ammount=200){
        // sets transaction-amounts details (all amounts are in cents)
        $this->transactionAmount = new TransactionAmount();
        $this->transactionAmount->setTotalAmount(0);
        $this->transactionAmount->setServiceFeeAmount(0);
        $this->transactionAmount->setPaymentAmount($ammount);
        $this->transactionAmount->setCurrency("LKR");
        $this->initRequest->setTransactionAmount($this->transactionAmount);
    }

它还在底部显示了这个错误

致命错误：调用上的成员函数SetTransactionMountForPay（） 无效 C:\xampp\htdocs\debug\u online\application\controllers\Billing.php on 第576行

---

在调用函数之前先创建一个对象

$this->My_payment_gate_way_init = new My_payment_gate_way_init();
$this->My_payment_gate_way_init->setTransactionAmountforPay($ammount);

---

在调用函数之前先创建一个对象

$this->My_payment_gate_way_init = new My_payment_gate_way_init();
$this->My_payment_gate_way_init->setTransactionAmountforPay($ammount);

---

对唐克斯兄弟。你救了我的命是的。。。唐克斯兄弟。你救了我的命。