I've come across two problems in the shopping cart which will cause problems with payment. As far as I know these have not been reported by others. The situation is as follows.

1. Goods are in the shopping cart, payment and shipping options selected and the correct price is shown at step 2. The customer moves on to step 4 of payment but before completing the transaction decides to use the form's "back" button to go back to step 2 and remove an item from the cart (not change quantity.) The total is adjusted correctly in step 2 but the original total shows at step 4 meaning that the customer would be overcharged if they continue.

2. The second problem is similar. The customer again goes back from step 4 to step 2 but then clicks on the "continue shopping" button and adds another item to the cart. This returns them to step 2 where the new total is correctly shown. When they now move on to step 4 the total price is shown as "undefined." The customer does not know how much to pay and the link to PayPal will fail as no amount data is sent.

There is a workround to this as any change to quantity, payment and mail options in step 2 trigger a recalculation and the correct amounts are shown. Unfortunately the customer does not know this.

If the "next" button in step 2 also triggered a recalculation it might solve these problems.

I hope this explains the problem clearly. I've played with a really simple test shopping cart quite a bit to see exactly what the problem is and can reproduce it consistently. Unfortunately it's the kind of behaviour real ife customers display when changing their mind about what they want to buy.

I'll be interested to see if others have had the same problem.

Hope this helps, Ron.