In-App purchase testing not returning product identifier

I signed in to itunes connect and created my app by entering all informations and screenshots required. Currently the status is "Prepare for Submission"(Am I supposed to "submit for review" before I could test in-app purchase?). I went to the In-App Purchases section and added my in-app purchase with all the product id, apple id, type, and screenshot setup. The status is currently "Ready to Submit". I write the code to test in-app purchase, but the product identifier that I setup in itunes connect is not found. What did I do wrong?

Code for testing itunes connect:

- (void)requestProUpgradeProductData
{

    NSSet *productIdentifiers = [NSSet setWithObject:@"-->my product identifier here<--" ];

    productsRequest = [[SKProductsRequest alloc] initWithProductIdentifiers:productIdentifiers];
    productsRequest.delegate = self;
    [productsRequest start];

}

- (void)productsRequest:(SKProductsRequest *)request didReceiveResponse:(SKProductsResponse *)response
{

    NSArray *products = response.products;

    proUpgradeProduct = [products count] == 1 ? [products firstObject]  : nil;
    if (proUpgradeProduct)
    {
        NSLog(@"Product title: %@" , proUpgradeProduct.localizedTitle);
        NSLog(@"Product description: %@" , proUpgradeProduct.localizedDescription);
        NSLog(@"Product price: %@" , proUpgradeProduct.price);
        NSLog(@"Product id: %@" , proUpgradeProduct.productIdentifier);
    }

    for (NSString *invalidProductId in response.invalidProductIdentifiers)
    {
        NSLog(@"Invalid product id: %@" , invalidProductId);
    }

}