No invoice found

One of my customers recently (yesterday) placed an order and paid through PayPal. The confirmation of Payment came through from PayPal as normal. Nothing strange, the money is in my PayPal account, but I did not get an email from ZenCart with the invoice, the order does NOT show up in my admin area, and when I log into the customers account (I use Master password encryption), it does not show up in her history. I then placed a test order from my own account, and all of the notifications occurred as normal.

Why would I not be able to see what she ordered?

I have attempted to contact the customer to see if she saw anything different during the purchasing process, but I am waiting for her return call/email.

What version of Zencart, and Paypal IPN or Express ?

I am using v1.3.9f, and PayPal "Website Payments Standard"

That's probably your problem. I'd switch to the much more reliable Paypal Express (and upgrade to 1.3.9h).

PayPal worked fine, ZenCart Did Not. Her order is not showing up in my Admin site, or in her history

I'll let DrByte explain much better than I can, but it's an issue about Paypal and Zencart communicating properly. Express does, IPN not so much.

I will certainly look into it, and I appreciate your feedback. I am just trying to understand.