Virgilio,
Invoices can't be generated until at least 48 hours after the purchase. That's due to delays in PayPal allowing reports to be created and for them to be entered into our accounting software. I've taken note of your request, and we'll try to get you an invoice on Monday. If you don't hear from us by then, just let us know.
We'd love to have an automated invoice system, and it's something we're looking into.. but that won't be out for a while.
Hope that helps,
Alex