Store listing failed

Hi,

I have a big problem in the shop (IAP) of Healer Quest : people can pay, I receive the money, but they are not granted what they payed for. After testing for a moment, it appears that the store listing simply always fail. I don't think I'm doing anything wrong with my code.

Here is an image of how my IAP page goes in google play :

And here is a simplified capx file

Thanks for any help !