After I've created helper script that implements IDetailedStoreListener interface, my IAPButton stopped calling its OnPurchaseComplete or OnPurchaseFailed events. It does open test window with "Buy" and "Cancel" buttons, but these buttons don't call defined methods. If I remove IDetailedStoreListener object, button returns to normal. My script implements ProcessPurchase method and it is actually called when I press "Buy". It also returns PurchaseProcessingResult.Complete value. Is there something else I need to add?