It looks like product keys are being generated correctly. The "Pending" failures from earlier are now being completed by PayPal -- they're just being slow about it. Here's what I would recommend:
- Delete the generated product keys.
- Cancel any pending payments in PayPal and the sandbox.
- Revert the paychecker.aspx.vb file to the one included in the Web API Pack.
Then run a single sandbox payment with the currency & price set to what you want. Set the quantity to something you haven't used before so you can tell that this is a new test. Then wait for it to be completed.
Does this make sense?