Every time I go to add an in-app purchase to one of my apps, I forget the pattern that was set up for my Product Id. I like to use the reverse domain and the product name tagged on the end like Apple suggests.
A product identifier is a string used to uniquely identify every product you wish to sell from your application. The App Store uses it to retrieve information about a product. It is a string identifier that can only contain alphanumeric (A-Z,a-z,0-9), underscore (_), and period (.) characters. You can use any sequence of these characters for your identifier. However, we recommend that you use the reverse domain name style (for example,
com.companyname.application.productid) when creating your identifier
Hopefully by writing this post it will help me remember that I have this set up this way. Burned a couple of hours trying to figure it out and it was right there all along.