google.iap.billing not working

When using the google.iap.billing plugin, after the purchase, the purchase is returned immediately and a message is sent to the mail:
Test purchase canceled due to lack of confirmation. You must confirm all purchases. If this is not done, the funds will be returned to customers. More details:

What am I doing wrong? Does everything work for everyone? There is nothing in the documentation about proof of purchase.

I believe was issue was being discussed over here before but I’m not sure how to fix the problem: New Google IAP Plugin and IAP Badger

Maybe @troylyndon could step in.

i’m currently also trying to implement IAP’s (google and apple) in my project and I’m losing my freaking mind. the documentation is atrocious and vague, can’t get any product info to load

okay guys. Sometime today I will write-up a document with exactly how I implemented the new Google Billing successfully. You should be aware that I’m seeing a 5% crash rate on non-Google Play installs of my app and I seriously have no idea why. Perhaps Google implemented their new billing as a means to stop non-Google Play installs, but it still messes up the vitals for my app and that makes me crazy.

Nevertheless, I will write a detailed doc (a page or two) with precise details on not only the build.settings simple change, but how the callback has to be modified.

Thanks. I solved my problem by adding proof of purchase. But it is still unclear how to delete an in-game purchase when the user cancels the order.