Paypal can't send payment

-- url of the page with the problem -- : www.gorinpianotales.org/
-- HikaShop version -- : 2.3.5
-- Joomla version -- : 3.3.6
-- Browser(s) name and version -- : Firefox

Hello,

I have a problem with the Paypal-payment method.

The shop works fine. I have only one payment-method and that is Paypal.
At the end of the checkout, the Paypal-Website comes up. Everything is fine and all the informatio are correct (Total, Details of the order).
I can login into Paypal and confirm. Then there is the last step at Paypal pressing a button like "Pay Now".

After that the problem start: Paypal cancel the payment and give out an error-message:
"We're sorry, but we can't send your payment right now."

I tried the same from a german Paypal-Account and I have the same problem but it gives me a little bit more information... I translate:
"This invoice is still payed. To get more information, call you dealer."

Today I had a very long phonecall with the Paypal-Support. After some checks they told me that the problem is the at Hikashop. Maybe Hikah send no correct order numbers. They had same problems with another shop-software and in that case it was a bug in the software at the end.

By the way I did one correct payment - it was the first test. But after that I only got the messages.

I checked the order-numbers at Hikashop and I wonder that they were all empty. It is only an idea but could this cause the problem? How can I fix it? Do you have another idea?

You can try it out if you like at the shop. If you send money (the english guidebook for teachers as ebook is cheapest product), I will send the money back to you but you want have success to send money at the end

I put two screenshots onto this email.

Thanks for your help!

Hi,

You must have deleted your "Order/Invoice number format" in the system configuration.

See here: www.hikashop.com/support/support/documen...nfig.html#main_order

Hello,

all these setiings are untouched from me and the settup is "{automatic_code}" - please look at screenshot I uploaded...
I also upload the setting of the Paypal-Module.

All the best,

Frank