implementing in app billing for qt android app: product not registered

[vudangkhoa2906]

i registered a subscription on google play console

and then in the app, i have this code snippet

        Product {
            id: product_223
            identifier: "223"
            type: Product.Unlockable

            property bool purchasing: false

            onPurchaseSucceeded: {
                console.log("purchase succedded");
            }

            onPurchaseFailed: {
                console.log("purchase failed");
            }
            onPurchaseRestored: {
                console.log("restore succedded");
            }

            onStatusChanged: {
                switch (status) {
                    case Product.PendingRegistration: console.debug("DEBUG_228_9: Registering " + identifier); break
                    case Product.Registered: console.debug(identifier + "DEBUG_228_10: registered with price " + price); break
                    case Product.Unknown: console.debug(identifier + "DEBUG_228_11: was not found in the market place"); break
                }
            }
        }

when i run the app, the log informs me that the product was not found in the market place (aka status Product.Unknown)
why is this happening? could any tell me where i did wrong? or is there another way to inplement in app billing?