order number not appearing on email receipt

Hi Eric - Attached is a copy of the confirm page. I checked the Store Order Summary, and the Order ID was not bound to the session value. I then added it, and an order number showed up on the next email receipt. The order number, however, was the first existing order number in the orders database and not the one it should have been. The next time I tried it, it was back to no order number on the email receipt again, so that did not resolve the problem.

I have seen an order number appear intermittently, say, 2 or 3 times in the approximately 100 test orders that I put through using the one administrator account, and the four visitor accounts I set up.

I hope you can help me with this problem, as it is the last remaing problems I have before I can upload the site to my client's server for testing and training.

The store is for taking orders only and does not have a payment gateway.