Swift In-App purchases sandbox tester error

I am implementing the In-App purchases function today, and I just followed the tutorial step by step, created sandbox testers, wrote the code, and it says

<SKPaymentQueue: 0x282e50860>: Payment completed with error: Error Domain=ASDServerErrorDomain Code=3502 "This item is not available." UserInfo={NSLocalizedDescription=This item is not available.

Why is "This item is not available."? I searched the relevant information online, but there is no answer for it.

Here is my code

@IBAction func purchaseButtonPressed(_ sender: UIButton) {
       print("PRESSED")
       purchaseApp()
   }
   
   func purchaseApp() {
       let productID = "com.crazycat.Reborn.FullFuctionalities"
       if SKPaymentQueue.canMakePayments() {
           let paymentRequest = SKMutablePayment()
           paymentRequest.productIdentifier = productID
           SKPaymentQueue.default().add(paymentRequest)
       } else {
           print("Can't make payments")
       }
   }

func paymentQueue(_ queue: SKPaymentQueue, updatedTransactions transactions: [SKPaymentTransaction]) {
       for transaction in transactions {
           if transaction.transactionState == .purchased {
               print("Thanks for shopping")
           } else if transaction.transactionState == .failed {
               print("purchase Failed")
           }
       }
   }